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Sample records for aso volcano japan

  1. Analysis of Fumarole Acoustics at Aso Volcano, Japan

    NASA Astrophysics Data System (ADS)

    McKee, K. F.; Yokoo, A.; Fee, D.; Huang, Y. C.; Yoshikawa, S.; Utsugi, M.; Minami, T.; Ohkura, T.

    2015-12-01

    The lowermost portion of large eruption columns is the momentum-driven, fluid flow portion known as a volcanic jet. The perturbation of the atmosphere from this region produces a sound known as jetting or jet noise. Recent work has shown that this volcanic jet noise produced by a volcano has similar characteristics as the sound from jet and rocket engines. The study of volcanic jet noise has gained much from laboratory jet engine studies; however, jet engines have been engineered to reduce noise thereby limiting their use as a comparison tool to the complex, ever-changing volcanic jet. Previous studies have noted that fumaroles produce jet noise without further detailed investigation. The goal of this work is to enhance our understanding of large-scale volcanic jets by studying an accessible, less hazardous fumarolic jet. We aim to characterize the acoustic signature of fumaroles and evaluate if fumarolic jets scale to that of large volcanic jets. To investigate this, we deployed a 6-element acoustic array at two different locations along the edge of the crater wall at Aso Volcano, Japan from early July through mid-August 2015. Approximately two months before this deployment, the pyroclastic cone within Aso's crater partially collapsed into the vent. The cone was constructed during both ash venting and strombolian-style explosive activity in the last year. After the deployment, on July 13 a new small vent opened on the southwest flank of the pyroclastic cone. The vent is several meters in diameter and has consistent gas jetting which produces audible jet noise. To better capture the acoustic signature of the gas jetting we moved the array to the southwestern edge of the crater. The array is 230 meters from the vent and is positioned 54 degrees from the vertical jet axis, a recording angle usually not feasible in volcanic environments. Preliminary investigations suggest directionality at the source and the influence of topography along the propagation path as

  2. Grounded electrical-source airborne transient electromagnetics (GREATEM) survey of Aso Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ito, Hisatoshi; Kaieda, Hideshi; Mogi, Toru; Jomori, Akira; Yuuki, Youichi

    2014-05-01

    Grounded electrical-source airborne transient electromagnetics (GREATEM), a type of semi-airborne electromagnetics, was used to examine Aso Volcano in south-west Japan, to verify its applicability to surveying deep subsurface resistivity structures. Comparison of the GREATEM resistivity values with those of ground-based transient electromagnetics (TEM) data, repeated GREATEM survey results at the same and different flight heights, and lithologic descriptions indicated that GREATEM can successfully identify underground structures as deep as ~800 m in rugged mountainous areas. An active volcanic region (Naka-Dake crater) was mapped as a low-resistivity zone from the surface to a depth of 100 m. This low-resistivity zone extended to the west-north-west, implying future volcanic activity in this area. Therefore, the GREATEM method is useful for surveying deep structures in large, inaccessible areas, such as volcanic provinces, in a quick, cost-effective way.

  3. Magma plumbing system of the Aso-3 large pyroclastic eruption cycle at Aso volcano, Southwest Japan: Petrological constraint on the formation of a compositionally stratified magma chamber

    NASA Astrophysics Data System (ADS)

    Kaneko, Katsuya; Inoue, Kazuhisa; Koyaguchi, Takehiro; Yoshikawa, Masako; Shibata, Tomoyuki; Takahashi, Toshiro; Furukawa, Kuniyuki

    2015-09-01

    Aso volcano has the largest caldera (18 × 25 km in diameter) in the southwestern Japan Island Arc, and it formed as the result of four large (VEI = 6-7) pyroclastic-eruption cycles. We study the penultimate large eruption cycle, the Aso-3 cycle, which occurred 123 ka with an ejecta volume of more than 150 km3. The processes in the pre-eruptive magma chamber and the magma genesis of the Aso-3 cycle were inferred from geological data, phenocryst chemistry, and whole-rock chemical and Sr-, Nd-, and Pb isotopic analyses of juvenile clasts. The geological and petrological data indicate that the pre-eruptive magma chamber was stratified compositionally into three layers: from top to bottom, silicic, intermediate, and mafic magma layers. The three magma layers had a uniform isotope composition, suggesting that all the magmas were generated from a single source. The silicic and intermediate magmas were not generated from the mafic magma by fractional crystallization. The silicic magma has higher Ni content (compatible element) than the mafic magma. This suggests that these magmas were produced by partial melting of the same mafic crust but with differing amounts of partial melting: the silicic magma was produced by a low degree of partial melting of the source rock without fractional crystallization, and the mafic magma was produced by a large degree of partial melting followed by fractional crystallization. The intermediate magma compositions plot on the tie line between the silicic magma and the melt of the mafic magma in variation diagrams, and the intermediate magma has phenocrysts whose compositions are identical with those in the silicic magma. This observation indicates that, before the Aso-3 eruption cycle, a two-layer stratified magma chamber of the silicic and mafic magmas was formed as a result of melting of the mafic crust, which was followed by formation of the intermediate layer as a result of interfacial mixing between the silicic magma and the melt of

  4. Sudden changes in the amplitude-frequency distribution of long-period tremors at Aso volcano, southwest Japan

    NASA Astrophysics Data System (ADS)

    Sandanbata, Osamu; Obara, Kazushige; Maeda, Takuto; Takagi, Ryota; Satake, Kenji

    2015-12-01

    We observed the activity of long-period tremors (LPTs) with a period of ~15 s at Aso volcano, Japan, during a 3 year period including the 2014 eruptions. The number of LPTs detected systematically increased 3 months before the Strombolian eruptions. LPT activity can be divided into five stages based on rapid changes in the maximum LPT amplitude. The amplitude-frequency relation follows an exponential distribution during each stage before the Strombolian eruptions, with different characteristic amplitudes for each stage, indicating that the scale of the source property changed in stages. However, during a stage that persisted for 6 days after the onset of Strombolian activity, the amplitude-frequency relation temporarily followed a power law distribution, indicating that the LPT source process no longer had a characteristic scale. In the last stage, the amplitude-frequency relation returned to an exponential distribution. We therefore conclude that the physical source of volcanic LPTs changed during the eruption period.

  5. Attempt of volcanomagnetic change detection by repeated aeromagnetic survey aeromagnetic survey on Aso and Kuju volcano, central Kyushu Japan -

    NASA Astrophysics Data System (ADS)

    Utsugi, M.; Tanaka, Y.; Kagiyama, T.; Okubo, A.

    2006-12-01

    Recently, geomagnetic field observation is successfully applied to many active volcanos to detect the volcano- magnetic changes. These observations are usually based on the continuous or repeated observation stations setting on the ground near the active area. From these observations, we can obtain high accurate information about the temporal geomagnetic field changes. But we can obtain only limited information about the special distribution of field changes. To interpret the geomagnetic field changes to underground heat transfer, we have to know the special distribution of the geomagnetic changes. To obtain the detailed information about the spatial distribution, aeromagnetic survey is usually used. In our study, we tried to use this method to detect the volcanomagnetic change. The main problem of aeromagnetic repeated observation is the difficulty of the observation point control. In the two flights, it is impossible that quite the same place flies. So that, it is very difficult to separate a change according to the volcanic activity and a spatial change. But, if we know detailed 3-D distribution of geomagnetic field and we can estimate the field intensity on the arbitrary point, we can correct the spatial variation of the repeated aeromagnetic survey data caused by the difference of flight position, and it may be possible to detect the field changes associated with the volcanic activities. For this purpose, we made very high density and low altitude helicopter-borne aeromagnetic survey on Aso and Kuju volcano in July 2002 and Dec. 2004. Each observation was done by a different approach. On Aso volcano, an extremely high density aeromagnetic observation was carried out. The survey area was selected as NS1200 x EW1200 x 300m region above the Nakadake crater which is the most active area on Aso volcano. The flight was made in 8 heights. The total numbers of measurements were about 8200. Based on the equivalent anomaly method, which is usually used to calculate the

  6. Origin and mode of emplacement of lithic-rich breccias at Aso Volcano, Japan: Geological, paleomagnetic, and petrological reconstruction

    NASA Astrophysics Data System (ADS)

    Furukawa, Kuniyuki; Uno, Koji; Shinmura, Taro; Miyoshi, Masaya; Kanamaru, Tatsuo; Inokuchi, Hiroo

    2014-04-01

    Takajosan breccia rocks are distributed around the southwestern caldera rim of the Aso Volcano in Japan. They are characterized by coarse lithic breccias with a pumiceous matrix. The proximal coarse lithic breccias are divided into the lower massive unit and the upper stratified unit. The lower massive lithic breccias tend to transform laterally into tuff breccias and pumiceous lapilli tuffs. Paleomagnetic results showed that all of the deposits were deposited at high temperatures of 175-560 °C. This was also supported by geological characteristics such as spatter clasts, clasts with a bread-crust texture, and weakly welded parts. These features clearly show that the deposits originated from pyroclastic density currents (PDCs). The dense lithic-rich lithofacies, low vesicularity of pumice, lack of plinian fall deposits, and radial distribution indicate that the deposits were derived from boil-over PDCs rather than plinian column-collapse PDCs. The SiO2 contents of the matrix glasses of the proximal lower massive breccia showed a progressive decrease from the bottom toward the upper part. We interpret that this chemical variation corresponds to chemical zonation of the magma chamber. This indicates that the massive deposits aggraded progressively from the base upwards (progressive aggradation), rather than through en masse freezing. The vertical lithofacies changes of the proximal breccias from the lower massive to the upper stratified units indicate that a sustained current in a quasi-steady state switched to an unsteady current with the progression of the volcanic activity.

  7. Origin and deformation of high porosity bands in the Takanoobane Rhyolite lava of Aso volcano, Japan

    NASA Astrophysics Data System (ADS)

    Furukawa, K.; Uno, K.

    2015-10-01

    In rhyolite lavas, the high porosity bands are often developed. They potentially act as pathways for gas movement to the lava surface. Since explosive activities of lavas are generally considered to be controlled by degassing system, understanding the origin and deformation process of the high porosity bands is important to assessing volcanic hazards. The Takanoobane rhyolite lava in the middle of Kyushu Island in SW Japan is effused at 51 ± 5 ka. The volume, flow length, and thickness are 0.14 km3, > 2 km, and about 90 m, respectively. The central crystalline part of the lava is characterized by the light-colored bands defined by the high porosity zone (HPZ). On the basis of geological and petrographical studies, we revealed that the HPZ was primary formed by ductile-brittle tearing of the lava (known as cavitation). According to the AMS results, the HPZs were subsequently stretched and flattened laterally during the concentric spreading of the lava. This deformation process could stretch the HPZ not only radially but also laterally. This effective stretching developed the HPZ into pervasive thin bands. Since the HPZs act as degassing pathways to the lava surface, the pervasive HPZ bands may play a role in providing volcanic gasses to void spaces created in surface fold hinges of rhyolite lavas. Thus, this degassing system may promote explosive activity of the lava surface.

  8. The oscillation model of hydrothermal dynamics beneath Aso volcano, southwest Japan after small eruption on May 2011: A new understanding model using repeated absolute and relative gravity measurement

    NASA Astrophysics Data System (ADS)

    Sofyan, Yayan; Nishijima, Jun; Fujimitsu, Yasuhiro; Yoshikawa, Shin; Kagiyama, Tsuneomi; Ohkura, Takahiro

    2016-01-01

    At the end of 2010, the seismic activity in Aso volcano intensely increased and water level in the Nakadake crater decreased until early in 2011, then was followed by a small eruption in May 2011. After the eruption and heavy rain, the volcanic activity subsided to calm period, crater bottom was refilled with water, and water level increased in the Nakadake crater. The next tremor reappeared in 2014 and tracked to eruption in November 2014. This eruptive pattern and water level variation in the crater repeatedly appeared on the surface, and it should be related to the hydrothermal dynamics beneath Aso volcano. We initiated the gravity measurements in relation to hydrothermal dynamics in the subsurface of Aso volcano using Scintrex CG-5 (549) and LaCoste Romberg type G-1016 relative gravimeter at 28 benchmarks in April 2011, one month before the eruption. The repeated gravity measurements continue to monitor Aso volcano with a series of the measurement after the eruption in every three months to a half year. We analyze the gravity variation from 2011 to 2014 between the time of the phreatic and strombolian eruption. The measurements covered the area more than 60 km2 in the west side of Aso caldera. A new gravity network was also installed in May 2010 at seven benchmarks using A10-017 absolute gravimeter, which re-occupied in October 2010, June 2011 and two benchmarks in June 2014. As a result, the gravity changes distinguish hydrothermal dynamic in the subsurface, which has a direct correlation to water level fluctuation in the crater, after the first eruption and before the second discharge. The monitoring data notice large gravity changes between the surveys at benchmarks around Nakadake crater and Kusasenri area. The simple 3D inversion models of the 4-D gravity data deduce the density contrast distribution beneath Aso volcano. The inversion and mass change result generate the oscillation typical as a new understanding model. The variation of the mass shows a

  9. Rupture process of the 2016 Kumamoto earthquake in relation to the thermal structure around Aso volcano

    NASA Astrophysics Data System (ADS)

    Yagi, Yuji; Okuwaki, Ryo; Enescu, Bogdan; Kasahara, Amato; Miyakawa, Ayumu; Otsubo, Makoto

    2016-07-01

    We constructed the rupture process model for the 2016 Kumamoto, Japan, earthquake from broadband teleseismic body waveforms (P-waves) by using a novel waveform inversion method that takes into account the uncertainty of Green's function. The estimated source parameters are: seismic moment = 5.1 × 1019 Nm (Mw = 7.1), fault length = 40 km, and fault width = 15 km. The mainshock rupture mainly propagated northeastward from the epicenter, for about 30 km, along an active strike-slip fault. The rupture propagation of the mainshock decelerated and terminated near the southwest side of the Aso volcano; the aftershock activity was low around the northeastern edge of the major slip area. Our results suggest that the rupture process of the mainshock and the distribution of aftershocks were influenced by the high-temperature area around the magma chamber of Mt. Aso.

  10. Magma plumbing system at the beginning of repeated caldera eruption: A case study on Aso-1 erupted about 270 ky ago from Aso caldera, SW Japan

    NASA Astrophysics Data System (ADS)

    Miyagi, I.; Hoshizumi, H.; Miyabuchi, Y.

    2015-12-01

    In order to understand the commencement of magma plumbing system of a polygenetic caldera, we started petrological study on the earliest eruptive product of Aso caldera, SW Japan. Aso caldera is one of the active volcano in Japan which have produced four stages (Aso-1, -2, -3, -4) of large-scale pyroclastic flow deposits 270 to 90 ky. ago. A suite of samples were collected from the bottom of Aso-1 pyroclastic flow deposit and from the underlying tephra layer (Ono et al., 1979). The tephra comprises more than 10 pumice fall units inter-layered by dark gray volcanic ash. For whole rock chemistry, coarser pumice fragments were separated. For mineral and glass chemistry, phenocrysts and glass particles were handpicked from the sieved 500-1000 um fractions under a binocular microscope. This fraction consist of plagioclase, orthopyroxene, variably vesiculated volcanic glass fragments, and clinopyroxene phenocrysts. They were analyzed using an electron micro-probe. The suite of samples are similar and major temporal change is the chemical composition of orthopyroxenes; those from upper horizon are relatively Mg rich. Anorthite content of plagioclase phenocryst is bimodal 49-53 mol. % (major) and 57-70 mol. % (minor). Silica content of matrix glass fall in a narrow range 68-70 wt. %. Temperature and oxygen fugacity were estimated to be 865-905 deg-C and FMQ+2 log unit, respectively, using ILMAT (Lepage, 2003). Pressure and water content of the magma are estimated to be 5-7 kbar and 0.5-1 wt. % H2O, respectively, using rhyolite-MELTS (Gualda et al., 2012) on the most undifferentiated tholeiitic basalt of Aso 4KC-03 (Hunter, 1998) to reproduce the observed composition of matrix glass (68-70 wt. % SiO2) and plagioclase (An 49-53 mol. %). The calcic plagioclase (An 57-70 mol. %), however, suggest that the basalt was initially hydrous and require magma degassing before the differentiation. If we assume degassing by magma convection in a conduit (Kazahaya et al., 1994), the

  11. Unzen Volcano, Japan

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This is a space radar image of the area around the Unzen volcano, on the west coast of Kyushu Island in southwestern Japan. Unzen, which appears in this image as a large triangular peak with a white flank near the center of the peninsula, has been continuously active since a series of powerful eruptions began in 1991. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 93rd orbit on April 15, 1994. The image shows an area 41.5 kilometers by 32.8 kilometers (25.7 miles by 20.3 miles) that is centered at 32.75 degrees north latitude and 130.15 degrees east longitude. North is toward the upper left of the image. The radar illumination is from the top of the image. The colors in this image were obtained using the following radar channels: red represents the L-band (vertically transmitted and received); green represents the average of L-band and C-band (vertically transmitted and received); blue represents the C-band (vertically transmitted and received). Unzen is one of 15 'Decade' volcanoes identified by the scientific community as posing significant potential threats to large local populations. The city of Shimabara sits along the coast at the foot of Unzen on its east and northeast sides. At the summit of Unzen a dome of thick lava has been growing continuously since 1991. Collapses of the sides of this dome have generated deadly avalanches of hot gas and rock known as pyroclastic flows. Volcanologists can use radar image data to monitor the growth of lava domes, to better understand and predict potentially hazardous collapses.

    Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The

  12. Exploration and monitoring geothermal activity using Landsat ETM + images. A case study at Aso volcanic area in Japan

    NASA Astrophysics Data System (ADS)

    Mia, Md. Bodruddoza; Nishijima, Jun; Fujimitsu, Yasuhiro

    2014-04-01

    Thermal activity monitoring in and around active volcanic areas using remote sensing is an essential part of volcanology nowadays. Three identical approaches were used for thermal activity exploration at Aso volcanic area in Japan using Landsat ETM + images. First, the conventional methods for hydrothermal alteration mapping were applied to find the most active thermal region after exploring geothermal indicator minerals. Second, we found some thermally highly anomalous regions around Nakadake crater using land surface temperature estimation. Then, the Stefan-Boltzmann equation was used for estimating and also monitoring radiative heat flux (RHF) from the most active region of about 8 km2 in and around Nakadake crater in the central part of the Aso volcano. To fulfill the required parameter in the Stefan-Boltzmann equation for radiative heat flux, the NDVI (Normalized differential vegetation index) method was used for spectral emissivity, and the mono-window algorithm was used for land surface temperature of this study area. The NDVI value was used to divide land-cover in the study area into four types: water, bare ground, mixed and vegetated land. The bare land was found within the most active region. Vegetation coverage area showed an inverse relationship with total RHF in this study as health of thermally stressed vegetation supports this relationship. The spatial distribution of spectral emissivity ranged from 0.94 to 0.99 in our study. Land surface temperature was estimated using a mono-window algorithm and was highest LST in 2008 and lowest in 2011. The results of RHF showed that the highest pixel RHF was found to be about 296 W/m2 in 2008. Total RHF was obtained of about 607 MW in 2002 and the lowest was about 354 MW in 2008. The RHF anomaly area was found the highest in 2002 and was lowest in 2011. The highest total heat discharge rate (HDR) obtained about 3918 MW in 2002 and lowest total HDR about 2289 MW in 2008 from this study area. But in the case of

  13. Steady subsidence of a repeatedly erupting caldera through InSAR observations: Aso, Japan

    NASA Astrophysics Data System (ADS)

    Nobile, Adriano; Acocella, Valerio; Ruch, Joel; Aoki, Yosuke; Borgstrom, Sven; Siniscalchi, Valeria; Geshi, Nobuo

    2016-04-01

    The relation between unrest and eruption at calderas is still poorly understood. Aso caldera, Japan, shows minor episodic eruptions, mainly phreatic, associated with steady subsidence. We analyse the recent deformation of Aso using SAR images from 1993 to 2011 and compare this with the eruptive activity. Although the dataset suffers from limitations (e.g., atmospheric effects, coherence loss, low signal to noise ratio), we observe a steady subsidence signal from 1996 to 1998, that suggests an overall contraction of a magmatic source below the caldera centre, from 4.5 to 7 km depth. Because of the similar volumes of the contracting source and erupted material, we propose that the contraction may have been induced by the release of the magmatic fluids feeding the eruptions. If confirmed by further data, this hypothesis suggests that degassing processes play a crucial role in triggering minor eruptions within open conduit calderas, as at Aso. These features underline the importance of defining any eruptive potential also from deflating magmatic systems with open conduit.

  14. Mineral and chemical variations within an ash-flow sheet from Aso caldera, Southwestern Japan

    USGS Publications Warehouse

    Lipman, P.W.

    1967-01-01

    Although products of individual volcanic eruptions, especially voluminous ash-flow eruptions, have been considered among the best available samples of natural magmas, detailed petrographic and chemical study indicates that bulk compositions of unaltered Pleistocene ash-flow tuffs from Aso caldera, Japan, deviate significantly from original magmatic compositions. The last major ash-flow sheet from Aso caldera is as much as 150 meters thick and shows a general vertical compositional change from phenocryst-poor rhyodacite upward into phenocryst-rich trachyandesite; this change apparently reflects in inverse order a compositionally zoned magma chamber in which more silicic magma overlay more mafic magma. Details of these magmatic variations were obscured, however, by: (1) mixing of compositionally distinct batches of magma during upwelling in the vent, as indicated by layering and other heterogeneities within single pumice lumps; (2) mixing of particulate fragments-pumice lumps, ash, and phenocrysts-of varied compositions during emplacement, with the result that separate pumice lenses from a single small outcrop may have a compositional range nearly as great as the bulk-rook variation of the entire sheet; (3) density sorting of phenocrysts and ash during eruption and emplacement, resulting in systematic modal variations with distance from the caldera; (4) addition of xenocrysts, resulting in significant contamination and modification of proportions of crystals in the tuffs; and (5) ground-water leaching of glassy fractions during hydration after cooling. Similar complexities characterize ash-flow tuffs under study in southwestern Nevada and in the San Juan Mountains, Colorado, and probably are widespread in other ash-flow fields as well. Caution and careful planning are required in study of the magmatic chemistry and phenocryst mineralogy of these rocks. ?? 1967 Springer-Verlag.

  15. Unzipping of the volcano arc, Japan

    NASA Astrophysics Data System (ADS)

    Stern, R. J.; Smoot, N. C.; Rubin, M.

    1984-02-01

    A working hypothesis for the recent evolution of the southern Volcano Arc, Japan, is presented which calls upon a northward-progressing sundering of the arc in response to a northward-propagating back-arc basin extensional regime. This model appears to explain several localized and recent changes in the tectonic and magrnatic evolution of the Volcano Arc. Most important among these changes is the unusual composition of Iwo Jima volcanic rocks. This contrasts with normal arc tholeiites typical of the rest of the Izu-Volcano-Mariana and other primitive arcs in having alkaline tendencies, high concentrations of light REE and other incompatible elements, and relatively high silica contents. In spite of such fractionated characteristics, these lavas appear to be very early manifestations of a new volcanic and tectonic cycle in the southern Volcano Arc. These alkaline characteristics and indications of strong regional uplift are consistent with the recent development of an early stage of inter-arc basin rifting in the southern Volcano Arc. New bathymetric data are presented in support of this model which indicate: (1) structural elements of the Mariana Trough extend north to the southern Volcano Arc. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. (3) rugged bathymetry associated with the rifted Mariana Trough is replaced just south of Iwo Jima by the development of a huge dome (50-75 km diameter) centered around Iwo Jima. Such uplifted domes are the immediate precursors of rifts in other environments, and it appears that a similar situation may now exist in the southern Volcano Arc. The present distribution of unrifted Volcano Arc to the north and rifted Mariana Arc to the south is interpreted not as a stable tectonic configuration but as representing a tectonic "snapshot" of an arc in the process of being rifted to form a back-arc basin.

  16. Unzipping of the volcano arc, Japan

    USGS Publications Warehouse

    Stern, R.J.; Smoot, N.C.; Rubin, M.

    1984-01-01

    A working hypothesis for the recent evolution of the southern Volcano Arc, Japan, is presented which calls upon a northward-progressing sundering of the arc in response to a northward-propagating back-arc basin extensional regime. This model appears to explain several localized and recent changes in the tectonic and magrnatic evolution of the Volcano Arc. Most important among these changes is the unusual composition of Iwo Jima volcanic rocks. This contrasts with normal arc tholeiites typical of the rest of the Izu-Volcano-Mariana and other primitive arcs in having alkaline tendencies, high concentrations of light REE and other incompatible elements, and relatively high silica contents. In spite of such fractionated characteristics, these lavas appear to be very early manifestations of a new volcanic and tectonic cycle in the southern Volcano Arc. These alkaline characteristics and indications of strong regional uplift are consistent with the recent development of an early stage of inter-arc basin rifting in the southern Volcano Arc. New bathymetric data are presented in support of this model which indicate: 1. (1) structural elements of the Mariana Trough extend north to the southern Volcano Arc. 2. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. 3. (3) rugged bathymetry associated with the rifted Mariana Trough is replaced just south of Iwo Jima by the development of a huge dome (50-75 km diameter) centered around Iwo Jima. Such uplifted domes are the immediate precursors of rifts in other environments, and it appears that a similar situation may now exist in the southern Volcano Arc. The present distribution of unrifted Volcano Arc to the north and rifted Mariana Arc to the south is interpreted not as a stable tectonic configuration but as representing a tectonic "snapshot" of an arc in the process of being rifted to form a back-arc basin. ?? 1984.

  17. Space Radar Image of Sakura-Jima Volcano, Japan

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The active volcano Sakura-Jima on the island of Kyushu, Japan is shown in the center of this radar image. The volcano occupies the peninsula in the center of Kagoshima Bay, which was formed by the explosion and collapse of an ancient predecessor of today's volcano. The volcano has been in near continuous eruption since 1955. Its explosions of ash and gas are closely monitored by local authorities due to the proximity of the city of Kagoshima across a narrow strait from the volcano's center, shown below and to the left of the central peninsula in this image. City residents have grown accustomed to clearing ash deposits from sidewalks, cars and buildings following Sakura-jima's eruptions. The volcano is one of 15 identified by scientists as potentially hazardous to local populations, as part of the international 'Decade Volcano' program. The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on October 9, 1994. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth. The image is centered at 31.6 degrees North latitude and 130.6 degrees East longitude. North is toward the upper left. The area shown measures 37.5 kilometers by 46.5 kilometers (23.3 miles by 28.8 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band vertically transmitted, vertically received; green is the average of L-band vertically transmitted, vertically received and C-band vertically transmitted, vertically received; blue is C-band vertically transmitted, vertically received.

  18. Broadband seismic observation at Kusatsu-Shirane volcano, Japan

    NASA Astrophysics Data System (ADS)

    Yamawaki, T.; Aoyama, H.; Terada, A.; Nogami, K.

    2011-12-01

    Kusatsu-Shirane volcano, central part of Japan, has repeated phreatic explosions with an interval of several decades. More than 25 years have passed since the last eruption in 1983. Currently persistent seismic and fumarolic activities are observed. Recently, a long tremor was observed in May 2011, for the first time in the last 3 years. The high-frequency tremor lasted for about 7 minutes and were observed by borehole seismometers. It was accompanied by a notable crustal deformation which lasted for about 4 minutes and observed by borehole tiltmeters. The source of the crustal deformation was estimated about 0.5 km to the southeast of Yugama, the main crater lake of the volcano. The location is at the margin of the observation network, which makes it difficult to locate the source precisely. The seismic network of the volcano has consisted of short-period seismometers. Thus very low frequency seismic events, which have often been observed at volcanoes with broadband seismometers, have not been investigated. In order to constrain such pressure sources, to understand better the relationships between high frequency tremor and low frequency deformation, and to investigate very low frequency events, we deployed 3-component seimometers at 3 points, surrounding the deformation source area. Two broadband seismometers, CMG-40T (f0=0.033 Hz) by Güralp Systems were installed to the north and east of the deformation source. And a short-period seismometer, L-4C (f0=1 Hz) by Mark Products, was installed to the south. The seismic data are continuously recorded. One and a half month passed at the time of abstract submission. Neither tremor nor very low frequency event have occurred to date.

  19. Carbon dioxide degassing by advective flow from Usu volcano, Japan.

    PubMed

    Hernández, P A; Notsu, K; Salazar, J M; Mori, T; Natale, G; Okada, H; Virgili, G; Shimoike, Y; Sato, M; Pérez, N M

    2001-04-01

    Magmatic carbon dioxide (CO2) degassing has been documented before the 31 March 2000 eruption of Usu volcano, Hokkaido, Japan. Six months before the eruption, an increase in CO2 flux was detected on the summit caldera, from 120 (September 1998) to 340 metric tons per day (September 1999), followed by a sudden decrease to 39 metric tons per day in June 2000, 3 months after the eruption. The change in CO2 flux and seismic observations suggests that before the eruption, advective processes controlled gas migration toward the surface. The decrease in flux after the eruption at the summit caldera could be due to a rapid release of CO2 during the eruption from ascending dacitic dikes spreading away from the magma chamber beneath the caldera. PMID:11292867

  20. Repetitive fracturing during spine extrusion at Unzen volcano, Japan

    NASA Astrophysics Data System (ADS)

    Lamb, O. D.; De Angelis, S.; Umakoshi, K.; Hornby, A. J.; Kendrick, J. E.; Lavallée, Y.

    2015-12-01

    Rhythmic seismicity associated with spine extrusion is a well-documented phenomenon at a number of dome-forming volcanic systems. At Unzen volcano, Japan, a 4-year dome-forming eruption concluded with the emplacement of a spine from October 1994 to February 1995, offering a valuable opportunity to further investigate seismogenic processes at dome-forming volcanoes. Using continuous data recorded at a seismic station located close to the dome, this study explores trends in the seismic activity during the extrusion of the spine. We identify a total of 12 208 volcano-seismic events in the period between October 1994 and February 1995. Hourly event counts indicate cyclic activity with periods of ∼ 40 to ∼ 100 h, attributed to pulsatory ascent defined by strain localisation and faulting at the conduit margins. Waveform correlation revealed two strong clusters (a.k.a. multiplets, families) which are attributed to fracturing along the margins of the shallow, ascending spine. Further analysis indicates variable seismic velocities during the spine extrusion as well as migration of the cluster sources along the spine margins. Our interpretation of the results from seismic data analyses is supported by previously published field and experimental observations, suggesting that the spine was extruded along an inclined conduit with brittle and ductile deformation occurring along the margins. We infer that changes in stress conditions acting on the upper and lower spine margins led to deepening and shallowing of the faulting sources, respectively. We demonstrate that the combination of geophysical, field and experimental evidence can help improve physical models of shallow conduit processes.

  1. Transpiration characteristics of forests and shrubland under land cover change within the large caldera of Mt. Aso, Japan

    NASA Astrophysics Data System (ADS)

    Miyazawa, Y.; Inoue, A.; Maruyama, A.

    2013-12-01

    Grassland within a caldera of Mt. Aso has been maintained for fertilizer production from grasses and cattle feeding. Due to the changes in the agricultural and social structure since 1950's, a large part of the grassland was converted to plantations or abandoned to shrublands. Because vegetations of different plant functional types differ in evapotranspiration; ET, a research project was launched to examine the effects of the ongoing land use change on the ET within the caldera, and consequently affect the surface and groundwater discharge of the region. As the part of the project, transpiration rate; E of the major 3 forest types were investigated using sap flow measurements. Based on the measured data, stomatal conductance; Gs was inversely calculated and its response to the environmental factors was modeled using Jarvis-type equation in order to estimate ET of a given part of the caldera based on the plant functional type and the weather data. The selected forests were conifer plantation, deciduous broadleaved plantation and shrubland, which were installed with sap flow sensors to calculate stand-level transpiration rate. Sap flux; Js did not show clear differences among sites despite the large differences in sapwood area. In early summer solar radiation was limited to low levels due to frequent rainfall events and therefore, Js was the function of solar radiation rather than other environmental factors, such as vapor pressure deficit and soil water content. Gs was well regressed with the vapor pressure deficit and solar radiation. The estimated E based on Gs model and the weather data was 0.3-1.2 mm day-1 for each site and was comparable to the E of grassland in other study sites. Results suggested that transpiration rate in growing was not different between vegetations but its annual value are thought to differ due to the different phenology.

  2. Mount Dutton volcano, Alaska: Aleutian arc analog to Unzen volcano, Japan

    NASA Astrophysics Data System (ADS)

    Miller, T. P.; Chertkoff, D. G.; Eichelberger, J. C.; Coombs, M. L.

    1999-04-01

    Holocene eruptions from Mount Dutton, a small Late Quaternary volcano near the tip of the Alaska Peninsula, bear strong physical and petrologic similarities to the 1990-1995 Unzen Fugendake eruption in Japan. The volcano had a protracted phase of effusive calcalkaline andesitic (54-59 wt.% SiO 2) cone-building in the late Pleistocene followed by an abrupt switch to more silicic (˜65 wt.% SiO 2) lavas, emplaced as a central summit cluster of steep-sided domes beginning in the early Holocene. The flanks of the volcano are mantled by pyroclastic flows, debris flows, and talus formed as a result of gravitational dome collapse. Disequilibrium mineral assemblages, including coexisting quartz and olivine in eruptive episodes ranging from the initial cone-building basaltic andesite lavas to the latest Holocene dacite domes, suggest extensive magma mixing. In addition, up to meter-sized, pillow-like cognate mafic enclaves of hornblende+plagioclase+glass are common in the latest of the summit dacite domes. Mineralogical evidence and bulk chemical data indicate the enclaves represent a high-alumina basalt parent with variable and subordinate reservoir contaminant, and the host lava is reservoir magma with variable and subordinate basaltic contaminant. Mount Dutton's history and petrology can be interpreted as reflecting the monotonous repetitive intrusion of mantle-derived mafic magma into a silicic crystal-rich crustal reservoir. During the Holocene, these injections resulted in the extrusion of partially crystallized, viscous, `sticky' central domes which typically failed by collapse resulting in small volume Merapi-type flowage deposits. We speculate that slow introduction of mafic magma into the silicic chamber leads both to enclave formation and to the effusive eruption style. Mount Dutton volcano experienced severe shallow earthquake swarms in 1984, 1988, and to a lesser extent in 1991; although none of these swarms resulted in an eruption, their epicenter distribution

  3. Origin of orange scoria from Omuroyama volcano, Japan

    NASA Astrophysics Data System (ADS)

    Fujiie, T.; Ohba, T.; Fujimaki, H.

    2003-12-01

    Origin of color variation of scoria from Omuroyama volcano, Izu peninsula, Shizuoka, Japan, was investigated. In the fresh glass domains, the compositions are homogeneous whereas the color of the scoria widely varies from black to orange. In fall units, the orange scoria clasts are homogeneously mixed with the black scoria clasts, and gray scoria clasts are included in some units. Continuous spectra of chemical (bulk clast) compositions correspond to the systematic variation of the scoria color from black to orange. Gray scoria has intermediate composition between orange and black scoria. The orange scoria is richer in Al, Fe3+, Si, and Ti and poorer in Ca, Mg, Na, and K than the black scoria. Back-scattered electron image observations of the orange scoria exhibit that the volcanic glass includes altered domains in which iron content is higher than the other area of the glass. Electron microprobe analyses, visible diffuse reflectance spectroscopy, and X-ray diffraction indicate the presence of goethite-like ferric iron hydroxide in volcanic glass. On possible explanation for the formation of ferric iron hydroxide is a leaching of iron by acid water including contributions from volcanic gasses and a precipitation-crystallization of iron hydroxides under near neutral pH conditions.

  4. Asymmetric deformation structure of lava spine in Unzen Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Miwa, T.; Okumura, S.; Matsushima, T.; Shimizu, H.

    2013-12-01

    Lava spine is commonly generated by effusive eruption of crystal-rich, dacitic-andesitic magmas. Especially, deformation rock on surface of lava spine has been related with processes of magma ascent, outgassing, and generation of volcanic earthquake (e.g., Cashman et al. 2008). To reveal the relationships and generation process of the spine, it is needed to understand a spatial distribution of the deformation rock. Here we show the spatial distribution of the deformation rock of lava spine in the Unzen volcano, Japan, to discuss the generation process of the spine. The lava spine in Unzen volcano is elongated in the E-W direction, showing a crest like shape with 150 long, 40 m wide and 50 m high. The lava spine is divided into following four parts: 1) Massive dacite part: Dense dacite with 30 m of maximum thickness, showing slickenside on the southern face; 2) Sheared dacite part: Flow band developed dacite with 1.0 m of maximum thickness; 3) Tuffisite part: Network of red colored vein develops in dacite with 0.5 m of maximum thickness; 4) Breccia part: Dacitic breccia with 10 m of maximum thickness. The Breccia part dominates in the northern part of the spine, and flops over Massive dacite part accross the Sheared dacite and Tuffisite parts. The slickenside on southern face of massive dacite demonstrates contact of solids. The slickenside breaks both of phenocryst and groundmass, demonstrating that the slickenside is formed after significant crystallization at the shallow conduit or on the ground surface. The lineation of the slickenside shows E-W direction with almost horizontal rake angle, which is consistent with the movement of the spine to an east before emplacement. Development of sub-vertical striation due to extrusion was observed on northern face of the spine (Hayashi, 1994). Therefore, we suggest that the spine just at extrusion consisted of Massive dacite, Sheared dacite, Tuffisite, Breccia, and Striation parts in the northern half of the spine. Such a

  5. Tephrostratigraphy and eruptive history of post-caldera stage of Toya Volcano, Hokkaido, northern Japan

    NASA Astrophysics Data System (ADS)

    Miyabuchi, Yasuo; Okuno, Mitsuru; Torii, Masayuki; Yoshimoto, Mitsuhiro; Kobayashi, Tetsuo

    2014-06-01

    A detailed tephrostratigraphy of Toya Volcano in Hokkaido, northern Japan has been constructed to evaluate the post-caldera eruptive history of the volcano. The tephrostratigraphic sequence preserved above the Toya ignimbrite reaches a total thickness of 8 m southeast of the caldera. After the caldera formation (115-112 ka), there was a long quiescent period of more than 60 ka years. The first post-caldera activity started with Nakajima Osarugawa pumice-fall deposit (Nj-Os) inside the caldera at 48 ka. Eruptive activity at Nakajima Volcano resumed at 30 ka with Nakajima Sekinai pumice-fall deposit (Nj-Sk), and was followed by continuous emission of fine ash including abundant accretionary lapilli. Soon after the Nakajima pyroclastic eruption Usu Volcano began its activity with discharges of basaltic ash and scoria (forming the Usu prehistoric tephra) and extrusion of homogeneous lavas namely Usu somma lava, resulting in the formation of the initial volcanic edifice. Subsequently, a large sector collapse occurred between 30 and 20 ka that emplaced the Zenkoji debris avalanche with little break after the formation of the initial Usu volcanic edifice. After the sector collapse, the volcano remained dormant for about 20-30 ka years. Eruptive activity at Usu Volcano resumed in 1663 AD with the most explosive plinian eruption in the post-caldera stage of Toya Volcano. Since then, seven eruptions have been recorded in 1769, 1822, 1853, 1910, 1943-1945, 1977-1978 and 2000 at multi-decadal interval. Total tephra volume during the post-caldera stage is estimated at about 0.9 km3 (dense rock equivalent: DRE), whereas total lava volume is calculated at about 2.3 km3. Therefore, the average magma discharge rate during the post-caldera stage of Toya Volcano is estimated at about 0.03 km3/ky, which is one or two order smaller than those of other Quaternary volcanoes in Japan.

  6. Structural evolution beneath Sakurajima Volcano, Japan, revealed through rounds of controlled seismic experiments

    NASA Astrophysics Data System (ADS)

    Tsutsui, Tomoki; Iguchi, Masato; Tameguri, Takeshi; Nakamichi, Haruhisa

    2016-04-01

    Structural evolution beneath an active volcano is detected as the variation of seismic reflectivity through controlled seismic experiments, which is interpreted as being associated with discharging magma. The target of the present study is Sakurajima Volcano, which is one of the most active volcanoes in Japan. Six rounds of seismic experiments with controlled sources have been conducted annually at the volcano. Two seismic reflection profiles are obtained from the datasets for each successful round of experiments. The experiments reveal clear annual variation in seismic reflectivity at a depth of 6.2 km in the northeastern part of Sakurajima. The reflectivity is maximum in December 2009 upon the first intrusion of magma and decreases gradually until December 2013, which coincides with the inflation and deflation cycle of Sakurajima Volcano. Reflectivity variation occurred in the embedded clear reflector at depth. An evolving sandwiched structure in the intermediate layer is used as the reflector model. Lower-velocity magma embedded in the intermediate layer and its succeeding velocity increment explain the variation range of reflectivity. This is interpreted as a temperature decrease associated with discharging magma at depth. The present study describes a new approach for instantaneously sensing magma properties and for monitoring active volcanoes.

  7. Descent of tremor source locations before the 2014 phreatic eruption of Ontake volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ogiso, Masashi; Matsubayashi, Hirotoshi; Yamamoto, Tetsuya

    2015-12-01

    On 27 September 2014, Ontake volcano, in central Japan, suddenly erupted without precursory activity. We estimated and tracked the source locations of volcanic tremor associated with the eruption at high temporal resolution, using a method based on the spatial distribution of tremor amplitudes. Although the tremor source locations were not well constrained in depth, their epicenters were well located beneath the erupted crater and the summit. Tremor sources were seen to descend approximately 2 km over a period of several minutes prior to the beginning of the eruption. Detailed analysis of the time series of tremor amplitudes suggests that this descent is a robust feature. Our finding may be an important constraint for modeling the 2014 eruption of Ontake volcano as well as for monitoring activities on this and other volcanoes.

  8. Earthquake characteristics before eruptions of Japan's Ontake volcano in 2007 and 2014

    NASA Astrophysics Data System (ADS)

    Zhang, Miao; Wen, Lianxing

    2015-09-01

    We detect earthquakes associated with Japan's Ontake eruptions in 2007 and 2014 using the match-and-locate method. Thirty-seven times more events (4949) than the Japan Meteorological Agency (JMA) catalog (133) and 30 times more events (1880) than the JMA catalog (62) are detected during the eruptions of 2007 and 2014, respectively. The detected earthquakes are further classified into three different types: long-period (LP) events, LP-associated events, and volcano-tectonic (VT) earthquakes. Both LP and LP-associated events are observed in the two eruptions. We suggest that the observed intense seismicity before both eruptions indicates the rewaking of Ontake volcano and might be used to predict its impending eruption in the long term. The temporal persistence and spatial concentration of LP and LP-associated events may be used to predict the eventual eruption and eruption location, and the maximum magnitude of the LP events may be used as an indicator of eruption magnitude.

  9. Multiparametric observation of volcanic lightning: Sakurajima Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Cimarelli, C.; Alatorre-Ibargüengoitia, M. A.; Aizawa, K.; Yokoo, A.; Díaz-Marina, A.; Iguchi, M.; Dingwell, D. B.

    2016-05-01

    We recorded volcanic lightning generated by Vulcanian explosions at Sakurajima Volcano using a synchronized multiparametric array. Physical properties of lightning are related to plume dynamics, and associated electromagnetic field variations are revealed by video observations (high speed and normal speed) together with infrasound and high sampling rate magnetotelluric signals. Data show that volcanic lightning at Sakurajima mainly occurs in the plume gas thrust region at a few hundred meters above the crater rim, where the overpressure of the turbulent volcanic jets determines the electrification of particles generating a complex charge structure in the growing plume. Organization of charges may be achieved at later stages when the plume transitions from the jet phase to the convective phase. Comparison with atmospheric sounding and maximum plume height data show that the effect of hydrometeors on flash generation at Sakurajima is negligible and can be more prudently considered as an additional factor contributing to the electrification of volcanic plumes.

  10. Magnetic constraints on the subsurface structure of Akita-Yakeyama volcano, northeast Japan

    NASA Astrophysics Data System (ADS)

    Okuma, S.

    1998-02-01

    Magnetic analyses have been conducted in and around Akita-Yakeyama volcano at the northwestern edge of the Sengan Geothermal Area, northeast Japan to reveal the regional and local subsurface structures of the area. First, a magnetization intensity mapping method has been applied to analyze aeromagnetic anomalies of the area. Generally, magnetization highs and lows lie on volcanic rocks which are normally and reversely magnetized, respectively. Magnetization lows with small amplitudes are distributed on hydrothermally altered areas. These results imply the usefulness of the method to estimate the young volcanic activities of Quaternary volcanic areas. Detailed magnetic modeling reveals the subsurface structure of Akita-Yakeyama volcano itself. Rock magnetic data from volcanic rocks, both from the surface and cores in the geothermal exploration wells, have been employed for the modeling. The resultant magnetic structure indicates the following: the surface volcanic rocks are underlain by granitic intrusions which have minimum thicknesses of about 2,000 m below the northern flank of volcano; in the southern flank, the surface volcanic rocks are underlain widely by the Old-Tamagawa Welded Tuffs which are reversely magnetized. These results show a good agreement with a geologic interpretation in and around the volcano, especially with a hypothesis of the existence of buried calderas below the present volcano.

  11. Scoria cone formation through a violent Strombolian eruption: Irao Volcano, SW Japan

    NASA Astrophysics Data System (ADS)

    Kiyosugi, Koji; Horikawa, Yoshiyuki; Nagao, Takashi; Itaya, Tetsumaru; Connor, Charles B.; Tanaka, Kazuhiro

    2014-01-01

    Scoria cones are common volcanic features and are thought to most commonly develop through the deposition of ballistics produced by gentle Strombolian eruptions and the outward sliding of talus. However, some historic scoria cones have been observed to form with phases of more energetic violent Strombolian eruptions (e.g., the 1943-1952 eruption of Parícutin, central Mexico; the 1975 eruption of Tolbachik, Kamchatka), maintaining volcanic plumes several kilometers in height, sometimes simultaneous with active effusive lava flows. Geologic evidence shows that violent Strombolian eruptions during cone formation may be more common than is generally perceived, and therefore it is important to obtain additional insights about such eruptions to better assess volcanic hazards. We studied Irao Volcano, the largest basaltic monogenetic volcano in the Abu Monogenetic Volcano Group, SW Japan. The geologic features of this volcano are consistent with a violent Strombolian eruption, including voluminous ash and fine lapilli beds (on order of 10-1 km3 DRE) with simultaneous scoria cone formation and lava effusion from the base of the cone. The characteristics of the volcanic products suggest that the rate of magma ascent decreased gradually throughout the eruption and that less explosive Strombolian eruptions increased in frequency during the later stages of activity. During the eruption sequence, the chemical composition of the magma became more differentiated. A new K-Ar age determination for phlogopite crystallized within basalt dates the formation of Irao Volcano at 0.4 ± 0.05 Ma.

  12. Finite-difference simulation of seismic wave propagation for explosion earthquakes at Sakurajima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Takenaka, H.; Fujioka, A.; Nakamura, T.; Okamoto, T.

    2013-12-01

    Sakurajima volcano is one of the most active volcanoes in Japan, which is located in a part of Kagoshima bay, i.e. Aira caldera, in the south of Kyushu island, Japan. It has elevation of 1117 m and three main peaks; Kita-dake (1117 m), Naka-dake (1060 meters) and Minami-dake (1040 m). Sakurajima is connected to the Osumi peninsula in the east. We construct a fully three-dimensional model of Sakurajima volcano and conduct numerical simulations of seismic wave propagation for eruption earthquakes at Sakurajima volcano with the finite-difference method (FDM, Nakamura et al., 2012, BSSA). Our FDM model area is 12 km x 15 km wide, which includes Sakurajima volcano around the center. Mesh size (size of each cubic cell) of the FDM model is 20 m. Seismic wave propagation is strongly affected not only by subsurface structure but also by topography of land and seafloor. For the surface model construction we employ the 50m-mesh DEM provided by the Geographical Survey Institute of Japan for land surface, and nearly-250m-mesh topographic data of Kishimoto (1999) for seafloor, while for the subsurface structure model construction we exploit the Japan Integrated Velocity Structure Model provided by the Headquarters for Earthquake Research Promotion. To incorporate the topography of land and seafloor into the FDM, a simple and accurate fluid-solid boundary condition is implemented, where the seawater is included in the sea area of the FDM model. We employ a simple pulse point source of a vertical single force or explosive (isotropic) type around the sea level depth in the volcano to excite seismic waves. The modeled frequency range of the simulation is lower than about 5 Hz. Our simulation results show rather complicated waveform and long duration, of which may come from a scattering effect due to the topography and a site effect due to the shallow surface layers on the seismic wave propagation. It suggests that appropriate modeling of effects of the topography on seismic wave

  13. Use of Unmanned Aircraft System (UAS) in Response to the 2014 Eruption of Ontake Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Mori, T.; Hashimoto, T.; Terada, A.; Shinohara, H.; Kazahaya, R.; Yoshimoto, M.; Tanaka, R.

    2015-12-01

    On Sept. 27, 2014, a phreatic eruption occurred at Ontake volcano (3067 m a.s.l.), central Japan. The eruption caused an unprecedented volcanic disaster in the last 70 years in Japan. Search and rescue operations started soon after the eruption until they were suspended due to snowfall in late October. Considering the potential hazards of further explosive events and the severe winter condition, an approach to the summit area after late October was very difficult. To reveal the condition of the volcanic activity and foresee the trend, we considered it important to carry out volcanic gas surveys for the dense plumes in the vicinity of the vents using an unmanned aircraft system (UAS). For the surveys at Ontake volcano, the UAS was expected to fly about 8 km roundtrip distance at an altitude of over 3000 m. A multicopter with 8 rotors was adopted and we targeted four types of plume monitoring using the UAS; in-plume monitoring of multiple gas concentrations, SO2 flux measurement with UV spectroscopy, thermography of the vents, and in-plume particle sampling. In order to meet the 1 kg payload of the multicopter, some of the instruments were slimmed down.The UAS campaigns at Ontake volcano were carried out on Nov. 20-21, 2014 and on Jun. 2, 2015 from the safety distance of 3-3.5 km away from the crater. With the UAS surveys, we revealed that the SO2/H2S ratios of volcanic gas were closer to the hydrothermal origin instead of direct magma degassing. The second survey also pointed out that the SO2 emission decreased down below 10 ton/day by June 2015, by taking an advantage of flying the vicinity of the vents before the plume was diluted. Our surveys showed decreasing activity of the volcano, together with the advantages of using UAS in volcano monitoring for inaccessible conditions.

  14. Seismic reflection survey of the crustal structure beneath Unzen volcano, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Matsumoto, Satoshi; Shimizu, Hiroshi; Onishi, Masazumi; Uehira, Kenji

    2012-05-01

    Unzen volcano is located in the western part of Kyushu, Japan. We carried out a seismic reflection survey at Unzen volcano in order to elucidate the structure of the volcano. Although the survey was conducted in a volcanic area under difficult conditions, such as artificial noises and a complex structure, we were able to resolve the structure beneath the profile using vibrator sources and a large number of stacking signals. The processed depth sections confirmed that Unzen volcano developed in a graben structure, as has been suggested in other geological studies. We imaged many subsurface normal faults shallower than 1 km. These faults, mostly covered with volcanic lava and deposits, were identified at the surface. Strong reflectors were found at a depth of approximately 3 km. They were located just above the pressure source of the latest eruption, as inferred from geodetic data. The geometric relationship between the reflection image, the pressure source location, and the lava dome suggests that the conduit from the lava dome could connect to the magma chamber located 4 km away from the lava dome.

  15. Three-dimensional resistivity modeling of GREATEM survey data from Ontake Volcano, northwest Japan

    NASA Astrophysics Data System (ADS)

    Abd Allah, Sabry; Mogi, Toru

    2016-05-01

    Ontake Volcano is located in central Japan, 200 km northwest of Tokyo and erupted on September 27, 2014. To study the structure of Ontake Volcano and discuss the process of its phreatic eruption, which can help in future eruptions mitigation, airborne electromagnetic (AEM) surveys using the grounded electrical-source airborne transient electromagnetic (GREATEM) system were conducted over Ontake Volcano. Field measurements and data analysis were done by OYO Company under the Sabo project managed by the Ministry of Land, Infrastructure, Transport and Tourism. Processed data and 1D resistivity models were provided by this project. We performed numerical forward modeling to generate a three-dimensional (3D) resistivity structure model that fits the GREATEM data where a composite of 1D resistivity models was used as the starting model. A 3D electromagnetic forward-modeling scheme based on a staggered-grid finite-difference method was modified and used to calculate the response of the 3D resistivity model along each survey line. We verified the model by examining the fit of magnetic-transient responses between the field data and 3D forward-model computed data. The preferred 3D resistivity models show that a moderately resistive structure (30-200 Ω m) is characteristic of most of the volcano, and were able to delineate a hydrothermal zone within the volcanic edifice. This hydrothermal zone may be caused by a previous large sector collapse.

  16. Network-based evaluation of infrasound source location at Sakurajima Volcano, Japan

    NASA Astrophysics Data System (ADS)

    McKee, K. F.; Fee, D.; Rowell, C. R.; Johnson, J. B.; Yokoo, A.; Matoza, R. S.

    2013-12-01

    An important step in advancing the science and application of volcano infrasound is improved source location and characterization. Here we evaluate different network-based infrasonic source location methods, primarily srcLoc and semblance, using data collected at Sakurajima Volcano, Japan in July 2013. We investigate these methods in 2- and 3-dimensions to assess the necessity of considering 3-D sensor and vent locations. In addition, we compare source locations found using array back azimuth projection from dual arrays. The effect of significant local topography on source location will also be evaluated. Preliminary analysis indicates periods of high- and low-level activity, suggesting different processes occurring in the upper conduit and vent. Network processing will be applied to determine signal versus noise, a technique which illuminates when the volcano is producing infrasound, to further investigate these processes. We combine this with other methods to identify the number and style of eruptions. By bringing together source location, timing of activity level, type of activity (such as tremor, explosions, etc.), and number of events, we aim to improve understanding of the activity and associated infrasound signals at Sakurajima Volcano.

  17. Volcanoes

    ERIC Educational Resources Information Center

    Kunar, L. N. S.

    1975-01-01

    Describes the forces responsible for the eruptions of volcanoes and gives the physical and chemical parameters governing the type of eruption. Explains the structure of the earth in relation to volcanoes and explains the location of volcanic regions. (GS)

  18. Volcanoes

    SciTech Connect

    Decker, R.W.; Decker, B.

    1989-01-01

    This book describes volcanoes although the authors say they are more to be experienced than described. This book poses more question than answers. The public has developed interest and awareness in volcanism since the first edition eight years ago, maybe because since the time 120 volcanoes have erupted. Of those, the more lethal eruptions were from volcanoes not included in the first edition's World's 101 Most Notorious Volcanoes.

  19. Volcanoes.

    ERIC Educational Resources Information Center

    Tilling, Robert I.

    One of a series of general interest publications on science topics, this booklet provides a non-technical introduction to the subject of volcanoes. Separate sections examine the nature and workings of volcanoes, types of volcanoes, volcanic geological structures such as plugs and maars, types of eruptions, volcanic-related activity such as geysers…

  20. Geothermal activity and energy of the Yakedake volcano, Gifu-Nagano, Japan

    SciTech Connect

    Iriyama, Jun

    1996-12-31

    The temperature of the most active solfatara in the summit crater of the Yakedake volcano (altitude 2,455 m Gifu-Nagano, Japan) was 92.2 and 129.4{degrees}C in September 1995 and in October 1994, respectively. The temperature of solfatara in the northern summit dome at an altitude of 2,240 to 2,270 m ranged from 68.2 to 92.5{degrees}C in September 1995. The water sample from a crater pond, Shoga-ike, located on the summit, showed a pH and electrical conductivity of 4.38 and 42.2 {mu}S/cm in October 1991, 4.35 and 42.4 {mu}S/cm in September 1992, 4.11 and 76.6 {mu}S/cm in October 1994, and 4.30 and 45.1 {mu}S/cm in September 1995, respectively. In 1960, the water sample from the same pond showed the pH and electrical conductivity of 3.7 and 80.8 {mu}S/cm, respectively. Although the values of pH and electrical conductivity in 1994 approached to the values at the volcano`s pre-eruption in 1960, the eruption in the summit dome did not occur in 1995. However, a large steam explosion occurred in the Nakanoyu area of the southeastern Mountainside of the volcano. The geothermal energy within the summit dome at an altitude of 2,050 to 2,455 m of the Yakedake volcano is calculated, using new data, to be about 4.8 x 10{sup 17} J, which represents a thermal power output of 5.1 x 10{sup 2} MW{sub th} averaged over 30 yrs.

  1. Unspiked K-Ar geochrolonology of Zao Volcano, Northeast Japan: Reconstruction of the volcanic stages

    NASA Astrophysics Data System (ADS)

    Yamasaki, S.; Ban, M.; Oikawa, T.

    2014-12-01

    We report new unspiked K-Ar ages for lavas corrected from the Zao volcano, northeast Japan. Unspiked K-Ar dating method (peak comparison method) enables mass fractionation correction of initial Ar ratio, and this method has been applied successfully to young lavas, especially younger than 0.5 Ma, with high atmospheric contamination. Zao volcano is the first volcano that is demonstrated the reliability of the mass fraction corrected ages by Takaoka et al. (1989). They reported 30 ages for central Zao volcano, and However, not all units are covered and some data contradict the stratigraphy probably because of low-K and/or excess Ar contamination. Based on new geological and geochrolonogical study, the volcanic activity can be divided into six stages. Stage I: subaqueous eruptions of low-K tholleiitic basaltic to andesitic magmas occured in central part at around 1 Ma. Stage II: andesitic northwestern edifice was formed at ca. 0.5 Ma. Stage III: several small to meddle sized andesitic to deictic edifices were formed at western part during ca. 0.35-0.25 Ma. Stage IV: andesitic to dacitic lavas swelled out from central summit area and the main edifice was formed during ca. 0.25-0.20 Ma. Stage V: andesitic lava flows with pyroclastic materials erupted from several vents during ca. 0.13-0.04 Ma. Several lava flows younger than 0.05 Ma were first dated on this study. Stage VI: The most recent stage of Zao volcano began at ca. 35 ka, when the horseshoe-shaped Umanose calderawas formed.

  2. The October 16, 2013 rainfall-induced landslides and associated lahars at Izu Oshima Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Miyabuchi, Yasuo; Maeno, Fukashi; Nakada, Setsuya

    2015-09-01

    Intense rainfall related to the typhoon T1326 on October 15-16, 2013 (total 824 mm; maximum hourly rainfall 118.5 mm) triggered numerous landslides and associated lahars at Izu Oshima Volcano, the northernmost part of Izu Mariana volcanic arc, Japan. The landslides were concentrated mainly in a 2-km2 area located on the western slope of Izu Oshima Volcano. Most of the landslides were shallow soil slips (< 2 m thick) in unconsolidated fallout tephra layers overlying lava flows and pyroclastic rocks. The rupture surfaces of them were located near the base of Y1 tephra (AD 1777-1778) and/or the base of Y4 tephra (AD 1421). The Y1 and Y4 tephras differ from the underlying paleosols in permeability, grain size and degree of compaction. The saturated hydraulic conductivities of the paleosols were one to two orders of magnitude smaller than those of the overlying Y1 and Y4 tephras. Most landslides mobilized completely into lahars, traveling along stream channels or flat slopes and flooding at the foot of the volcano. The associated lahars severely damaged inhabited areas and caused thirty five fatalities. Although the lahars eroded slopes and transported boulders up to 1 m in diameter and a large amount of woody debris, they contained more than 90% of sand-to-silt-size particles, similar in composition to the original sliding materials. Sediment discharge volumes from three basins were estimated at 1.8-4.1 × 104 m3/km2, based on debris volumes trapped by sediment retention dams. The characteristics of rainfall-induced landslides and associated lahars at Izu Oshima Volcano in 2013 provide an important lesson about future non-eruption-related landslide and lahar hazards at tephra-rich volcanoes.

  3. Microbiological and Geochemical Characterization of the Deep Subsurface Environment: Kumano Mud Volcano, Nankai Trough, Japan

    NASA Astrophysics Data System (ADS)

    Case, D. H.; Ijiri, A.; Morono, Y.; Orphan, V. J.; Inagaki, F.

    2013-12-01

    Submarine mud volcanoes play an important environmental role by delivering deep-sourced fluids, elements, and hydrocarbons to the seafloor. These fluxes in turn support chemosynthetic benthic communities. However, due to difficulty in accessing the deep biosphere most mud volcano samples only represent the top one to several meters below seafloor (mbsf) obtainable by remotely operated vehicle (ROV) or gravity cores. Thus, the geochemical and microbiological conditions, as well as vertical homogeneity, deep within mud volcanoes remains poorly constrained. In 2012, using the deep-sea drilling vessel Chikyu, we drilled one of the most active submarine mud volcanoes in the Kumano forearc basin of the Nankai Trough, off the Kii Peninsula of Japan (33°67.581'N, 136°56.8085'E: 1,986.7 m in water depth). Cores were obtained down to 200 mbsf. Cell counts indicate the presence of microorganisms at relatively low abundance (less than 105 cells/cm3) throughout the cored depth. Molecular analyses reveal vertical heterogeneity in the microbial community composition, including specific depth horizons harboring putative methanogenic and methanotrophic phylotypes at >100 mbsf. Geochemical profiles indicate the potential for microbial activity and rate measurements with radiotracers revealed active homoacetogenesis rates that were 2-3 orders of magnitude higher than rates of homo- and acetoclastic methanogenesis. To assess active autotrophic, methanotrophic and heterotrophic populations, 13C- and 15N-amendment experiments with sediment samples collected from 15 and 115 mbsf were established and single cell stable isotope analyses with nanoSIMS are in progress. Our samples and analyses represent a unique observation of a subseafloor setting different from previously explored stratified sediments on continental margins and will allow further understanding of how submarine mud volcanoes contribute to geochemical and microbiological fluxes into the surface biosphere.

  4. Sakura-jima volcano in Japan as seen from STS-66 Atlantis

    NASA Technical Reports Server (NTRS)

    1994-01-01

    One of the world's most active volcanoes, Sakura-jima in southern-most Kyushu, Japan, erupts dozens of times a year. Volcanic eruptions are so much a part of of daily life in the city of Kagoshima (across the bay and west of Sakura-jima), that school children wear hard hats to school. This photo provides a nice clear view of Sakura-jima on a quiet day - only a plume of steam rises from the summit crater. The summit region is covered with gray ash from the frequent eruptions, and some of the rivers cutting down the mountain (especially the western drainages) appear to be filled with volcanic debris.

  5. A large self-potential anomaly on Unzen volcano, Shimabra peninsula, Kyushu island, Japan

    NASA Astrophysics Data System (ADS)

    Hashimoto, T.; Tanaka, Y.

    1995-02-01

    Self-potential (SP) observation was carried out in the summit area of Unzen, one of the active volcanoes in Kyushu island, Japan. We found a positive SP anomaly in the vicinity of the newly extruded lava dome. The potential difference across the anomaly exceeds 1000 mV per 500 m. Streaming potentials associated with subsurface hydrothermal convection seem to be the most reasonable mechanism for the positive anomaly. In association with the first emergence of the lava dome a sharp increase of SP was detected, which is considered to be a result of the growth of the hydro-thermal system.

  6. Lithospheric Contributions to Arc Magmatism: Isotope Variations Along Strike in Volcanoes of Honshu, Japan

    PubMed

    Kersting; Arculus; Gust

    1996-06-01

    Major chemical exchange between the crust and mantle occurs in subduction zone environments, profoundly affecting the chemical evolution of Earth. The relative contributions of the subducting slab, mantle wedge, and arc lithosphere to the generation of island arc magmas, and ultimately new continental crust, are controversial. Isotopic data for lavas from a transect of volcanoes in a single arc segment of northern Honshu, Japan, have distinct variations coincident with changes in crustal lithology. These data imply that the relatively thin crustal lithosphere is an active geochemical filter for all traversing magmas and is responsible for significant modification of primary mantle melts. PMID:8662469

  7. Explosion energy of the 2004 eruption of the Asama Volcano, central Japan, inferred from ionospheric disturbances

    NASA Astrophysics Data System (ADS)

    Heki, Kosuke

    2006-07-01

    The Japanese dense array of Global Positioning System recorded ionospheric disturbances as changes in Total Electron Content ~12 minutes after the September 1 2004 eruption of the Asama Volcano, Central Japan. The disturbance had a period of one and a quarter minutes and propagated as fast as ~1.1 km/s, suggesting its origin as the acoustic wave generated by the explosion. By comparing the disturbance amplitudes with those by a surface mine blast with a known energy, the overall Asama explosion energy is inferred to be about 2 × 1014 J.

  8. Episodic Deep Fluid Expulsion at Mud Volcanoes in the Kumano Forearc Basin, SE Offshore Japan

    NASA Astrophysics Data System (ADS)

    Hammerschmidt, S.; Kopf, A.

    2014-12-01

    Compressional forces at convergent margins govern a variety of processes, most prominently earthquakes, landslides and mud volcanoes in the forearc. Although all seem related to fluid pressure changes, mud volcanoes are not only characterized by expulsion of fluids, but also fluidized mud and clasts that got ripped-up during mud ascension. They hence provide information regarding mobilization depth, diagenetic overprint, and geodynamic pathways. At the Nankai Trough subduction zone, SE offshore Japan, mud volcanism id common and supposed to be related to seismogenic processes. During MARUM Expedition SO-222 with R/V SONNE, mud volcanoes in the Kumano forearc basin were mapped, cored and sampled. By extending the Integrated Ocean Drilling Program (IODP) Kumano transect landwards, 5 new mud volcanoes were identified by multibeam mapping. Cores revealed mud breccia with semi-consolidated silt- to claystone clasts and gaseous fluid escape structures, while the hemipelagic background sediments are characterized by intercalations of turbidites, ash layers and calcareous fossils. Clasts were subject to thin-section analyses, and the cores were sampled for XRD analyses and radiocarbon dating. Clasts showed prominent deformation structures, neomorphism and pores and fractures filled with polycrystalline quartz and/or calcite cement, probably formed during deep burial and early metamorphosis. Illite crystallinity based on XRD measurements varies between 0.24 and 0.38, which implies that the material originates from the Anchizone at depths ≥ 4 km. Radiocarbon dating revealed ages between 4450 and 30300 yr cal. BP, with age reversals occurring not earlier than 17000 yr cal. BP. Radiocarbon dating beneath turbidites and ash layers found at mud volcano #9 points to an episodic occurrence of these earthquake-related features in intervals of ca. 620 yr, while the mud volcano itself remained inactive. In summary, the preliminary results suggest that the mud volcanoes are nurtured

  9. Aeromagnetic survey using an unmanned autonomous helicopter over Tarumae Volcano, northern Japan

    NASA Astrophysics Data System (ADS)

    Hashimoto, Takeshi; Koyama, Takao; Kaneko, Takayuki; Ohminato, Takao; Yanagisawa, Takatoshi; Yoshimoto, Mitsuhiro; Suzuki, Eiichi

    2014-09-01

    Unmanned aerial vehicles (UAVs) have recently received attention in various research fields for their ability to perform measurements, surveillance, and operations in hazardous areas. Our application is volcano surveillance, in which we used an unmanned autonomous helicopter to conduct a dense low-altitude aeromagnetic survey over Tarumae Volcano, northern Japan. In autonomous flight, we demonstrated positioning control with an accuracy of ~10 m, which would be difficult for an ordinary crewed vehicle. In contrast to ground-based magnetic measurement, which is highly susceptible to local anomalies, the field gradient in the air with a terrain clearance of 100 to 300 m was fairly small at 1 nT/m. This result suggests that detection of temporal changes of an order of 10 nT may be feasible through a direct comparison of magnetic data between separate surveys by means of such a system, rather than that obtained by upward continuation to a common reduction surface. We assessed the temporal magnetic changes in the air, assuming the same remagnetising source within the volcano that was recently determined through ground surveys. We conclude that these expected temporal changes would reach a detection level in several years through a future survey in the air with the same autonomous vehicle.

  10. Underground structure of terrestrial mud volcanoes and abnormal water pressure formation in Niigata, Central JAPAN

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Shinya, T.; Miyata, Y.; Tokuyasu, S.

    2005-12-01

    Activity of mud volcano is thought to be caused by an abnormal water pressure generated in deep underground and make a serious problem for underground constructions such as railway tunnel, underground facility for radwaste and so on. It is important to investigate the underground structure of a mud volcano and the mechanism of abnormal water formation for site selection and safety assessment of such facilities. Serious trouble such as tunnel wall collapse due to the rock swelling has happened 180m deep under mud volcanoes. It took more than 10 years to excavate the section of 150 m long. 4 terrestrial mud volcanoes were found in the Tertiary sedimentary basin in Niigata, central Japan All the mud volcanoes are distributed along the rim of the topographic basin that is located at the NE-SW trending crest of mountainous area and distributed along the wing of anticline. Geological structure inside basin is heavily disturbed. The extinct mud volcano is exposed in the side-slope of newly constructed road and the internal vent structure of mud volcano can be observed. The vent is 30 m in diameter and is consisted of mud breccia and scaly network clay that is thought to be generated by hydro-fracturing and the following water-rock interaction between mudstone and groundwater. Groundwater erupted from mud volcano is highly saline with electric conductivity of 15 mS/cm and high 18 O/16 O isotope ratio of 1.2 parmillage. Also, the vitrinite reflectance is 1.5 to 1.9 % that is not expected in the sedimentary rocks exposed near ground surface. As a result, it is assumed that these erupted materials were introduced from the deep underground about 4000 m deep. CSA-MT geophysical exploration was carried out to survey the underground structure and obtained the profile of electrical resistivity from the surface to 800 m in depth. It is found that the disk-shaped low resistivity zone less than 1 m due to the high salinity content is identified in underground 600 m deep, 200 m thick

  11. Local-Scale Ambient Noise Tomography In and Around the Naruko Volcano, NE Japan

    NASA Astrophysics Data System (ADS)

    Tamura, J.; Okada, T.

    2014-12-01

    The 2008 Iwate-Miyagi Nairiku earthquake (M7.2) occurred along a fault in northeastern Japan. The focal area is surrounded with four quaternary volcanoes: Yakeishi, Kurikoma, Onikobe caldera, and Naruko volcano. In a previous study of Okada et al. (2014), they conducted seismic tomography in and around the focal area, and found low velocity zones (LVZ) with high Vp/Vs beneath the volcanoes. They suggest that those LVZs could correspond to areas with over-pressurized fluids, which promoted the occurrence of the earthquake. One of their remaining issues in their study, however, is that a possible LVZ was not clearly found beneath the Naruko volcano, which is located on the south edge of aftershock distribution. In this study, we performed ambient noise tomography in an attempt to identify the possible LVZ beneath Naruko using seismic stations, which are densely deployed in the Naruko volcanic area. After the pre-processing (Bensen et al. 2007) to obtain Rayleigh-wave Green's function, we measure phase velocity dispersion curves as described in Lin et al. (2008). Then, surface-wave tomography (Barmin et al. 2001) is performed from 0.15 Hz to 0.5 Hz with a frequency step of 0.05 Hz. As a final step, we invert phase velocities for a 1-D Vs model at each grid point by nonlinear inversion(Tarantola and Valette, 1982). The Vs structure shows two LVZs beneath Naruko and Onikobe. The LVZ of Naruko, however, is merged into that of Onikobe at around 4 km depths and is not resolved in deeper crust.

  12. Megathrust earthquakes in Japan and Chile triggered multiple volcanoes to subside

    NASA Astrophysics Data System (ADS)

    Takada, Y.; Pritchard, M. E.; Fukushima, Y.; Jay, J.; Aron, F. A.; Henderson, S.; Lara, L. E.

    2012-12-01

    With spaceborne interferometric synthetic aperture radar (InSAR) analysis, we found that two recent megathrust earthquakes, the 2011 Mw 9.0 Tohoku earthquake in Japan (March 11, 2011) and the 2010 Mw 8.8 Maule earthquake in Chile (February 27, 2010), have triggered unprecedented subsidence of multiple volcanoes. There are strong similarities in the characteristics of the surface deformation in Chile and Japan; (1) the maximum amount of subsidence is about 15 cm, (2) the shape of subsidence areas exhibit elliptic shape elongated in the North-South direction -- perpendicular to the principal axis of the extensional stress change, and (3) most of the subsidence was aseismic. These similarities imply that volcanic subsidence from megathrust earthquakes is a ubiquitous phenomenon. In both areas, we found that hydro-thermal reservoirs (including water, gas, and possibly magma) would play key roles in the subsidence. Further continuous monitoring is necessary to determine if the surface subsidence leads to additional volcanic unrest. For the 2011 Tohoku Earthquake, we used SAR data acquired before and after the mainshock by ALOS (PALSAR). By removing long wave-length phase trend from InSAR images, we obtained the localized subsidence signals at five active volcanoes: Mt. Akitakoma, Mt. Kurikoma region, Mt. Zao, Mt. Azuma, and Mt. Nasu. All of them belong to the volcanic front of Northeast Japan and so they are among the closest volcanoes to the earthquake. The maximum amount of subsidence reaches 15 cm at Mt. Azuma. GPS data from two volcanoes also indicate surface subsidence consistent with the satellite radar observations. Furthermore, the GPS data show that the subsidence occurred immediately after the earthquake. According to numerical modelling, the observed subsidence can be explained by the co-seismic response of fluid-filled ellipsoid with horizontal dimensions of 10-40 × 5-15 km beneath each volcano. For the 2010 Maule Earthquake, we extracted the localized

  13. Characterization of fine volcanic ash from explosive eruption from Sakurajima volcano, South Japan

    NASA Astrophysics Data System (ADS)

    Nanayama, F.; Furukawa, R.; Ishizuka, Y.; Yamamoto, T.; Geshi, N.; Oishi, M.

    2013-12-01

    Explosive volcanic eruptions can affect infrastructure and ecosystem by their dispersion of the volcanic particle. Characterization of volcanic particle expelled by explosive eruption is crucial for evaluating for quantitative hazard assessment by future volcanic eruption. Especially for fine volcanic ash less than 64 micron in diameter, it can disperse vast area from the source volcano and be easily remobilized by surface wind and precipitation after the deposition. As fine volcanic ash is not preserved well at the earth surface and in strata except for enormously large scale volcanic eruption. In order to quantify quantitative characteristics of fine volcanic ash particle, we sampled volcanic ash directly falling from the eruption cloud from Showa crater, the most active vent of Sakurajima volcano, just before landing on ground. We newly adopted high precision digital microscope and particle grain size analyzer to develop hazard evaluation method of fine volcanic ash particle. Field survey was performed 5 sequential days in January, 2013 to take tamper-proof volcanic ash samples directly obtained from the eruption cloud of the Sakurajima volcano using disposable paper dishes and plastic pails. Samples were taken twice a day with time-stamp in 40 localities from 2.5 km to 43 km distant from the volcano. Japan Meteorological Agency reported 16 explosive eruptions of vulcanian style occurred during our survey and we took 140 samples of volcanic ash. Grain size distribution of volcanic ash was measured by particle grain size analyzer (Mophologi G3S) detecting each grain with parameters of particle diameter (0.3 micron - 1 mm), perimeter, length, area, circularity, convexity, solidity, and intensity. Component of volcanic ash was analyzed by CCD optical microscope (VHX-2000) which can take high resolution optical image with magnifying power of 100-2500. We discriminated each volcanic ash particle by color, texture of surface, and internal structure. Grain size

  14. The “anomalous cedar trees” of Lake Ashi, Hakone Volcano, Japan

    USGS Publications Warehouse

    Oki, Y.

    1984-01-01

    On the bottom of Lake Ashi at Hakone, Japan, there stand great trees that, since ancient times, have been widely known as the "Anomalous Cedar Trees" of Ashi. It is not known why these trees grow on the bottom of the lake, and it remains one of the mysteries of Hakone. It was formerly thought that, at the time Lake Ashi was born, a great forest of cedar trees which was growing in the caldera of the volcano sank into the water. From radioactive carbon dating techniques, it is known that a steam explosion in the Kami Mountains created the caldera approximately 3,000 years ago. The age of the "Anomalous Cedars" is placed at approximately. 

  15. A magma-hydrothermal system beneath Hakone volcano, central Japan, revealed by highly resolved velocity structures

    NASA Astrophysics Data System (ADS)

    Yukutake, Yohei; Honda, Ryou; Harada, Masatake; Arai, Ryuta; Matsubara, Makoto

    2015-05-01

    High-resolution images of subsurface structures are necessary to understand the transport processes of crustal fluids from deep magma sources and their relationship to earthquake swarms in active volcanic regions. Based on a seismic tomography approach, we have developed a new model for the magma-hydrothermal system beneath Hakone volcano, central Japan, where shallow earthquake swarms and crustal deformation associated with inflation of an open-crack source are often observed. By applying travel-time data for local earthquakes to a tomographic inversion, we obtained highly resolved seismic velocity structures that show a region of low P-wave velocity (Vp), low S-wave velocity (Vs), and high Vp/Vs ratios at depths of 10-20 km beneath the volcano, corresponding to the location of the open-crack source. We suggest that the high Vp/Vs ratios represent a deep magma chamber with a high concentration of melt and/or fluids. Deep low-frequency earthquakes, located just beneath this high Vp/Vs zone, may indicate that magmatic fluids are supplied from below. Above the high Vp/Vs zone, a region of low Vp, low Vs, and low Vp/Vs ratios exists at depths of 3-10 km, suggesting the presence of crack-filled water or CO2 supplied from the inferred deep magma chamber. Many earthquake swarms occur in this low Vp/Vs zone, indicating that crustal fluids play an important role in generating the swarms. Similar relationships between magma reservoirs, overlying hydrothermal systems, and swarm activity have been reported from other volcanic areas and thus may be a ubiquitous feature beneath active volcanoes.

  16. Aeromagnetic constraints on the subsurface structure of Usu Volcano, Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Okuma, Shigeo; Nakatsuka, Tadashi; Ishizuka, Yoshihiro

    2014-11-01

    Usu Volcano, Hokkaido, Japan consists mainly of dacitic volcanic rocks underlain by basaltic somma lava and Pliocene-Pleistocene andesitic volcanic rocks, and erupts every 20-30 years. The most recent eruption, in 2000, was the first since 1978. We conducted a helicopter-borne high-resolution aeromagnetic survey almost three months after the start of this eruption. We calculated magnetic anomalies on a smoothed observation surface using a reduction method, assuming equivalent anomalies below the actual observation surface. We conducted three-dimensional (3D) imaging of magnetic anomalies to constrain the subsurface structure. Our model indicates that there are magnetisation highs in the main edifice of Usu Volcano, which may reflect the subsurface distribution of the Usu somma lava. Meanwhile, magnetisation lows lie north-west of the Nishi-Yama Craters Area and on Higashi-Maruyama Cryptodome, where nearby Pliocene and Pleistocene volcanic rocks, respectively, are found. The reverse magnetisation observed at outcrops close to these sites could explain the magnetisation lows. Although the survey improved our understanding of the surface and subsurface distribution of volcanic rocks in the edifice and basement of Usu Volcano, some limitations remain. No information about the magmas intruded during the recent eruptions in 1977-1978 and 2000 was obtained by the survey, though some of these intrusions were revealed by other geophysical data. The small magnetic contrast between the intruded magmas and their host rocks is the most probable reason. Perhaps the intruded magmas (in particular, those of the most recent eruption) had not cooled enough to become strongly magnetised by the time the survey was conducted.

  17. Monitoring eruption activity from temporal stress changes at Mt. Ontake volcano, Japan

    NASA Astrophysics Data System (ADS)

    Terakawa, T.; Kato, A.; Yamanaka, Y.; Maeda, Y.; Horikawa, S.; Matsuhiro, K.; Okuda, T.

    2015-12-01

    On 27 September 2014, Mt. Ontake in Japan produced a phreatic (steam type) eruption with a Volcanic Explosivity Index value of 2 after being dormant for seven years. The local stress field around volcanoes is the superposition of the regional stress field and stress perturbations related to volcanic activity. Temporal stress changes over periods of weeks to months are generally attributed to volcanic processes. Here we show that monitoring temporal changes in the local stress field beneath Mt. Ontake, using focal mechanism solutions of volcano-tectonic (VT) earthquakes, is an effective tool for assessing the state of volcanic activity. We estimated focal mechanism solutions of 157 VT earthquakes beneath Mt. Ontake from August 2014 to March 2015, assuming that the source was double-couple. Pre-eruption seismicity was dominated by normal faulting with east-west tension, whereas most post-eruption events were reverse faulting with east-west compression. The misfit angle between observed slip vectors and those derived theoretically from the regional (i.e., background) stress pattern is used to evaluate the deviation of the local stress field, or the stress perturbation related to volcanic activity. The moving average of misfit angles tended to exceed 90° before the eruption, and showed a marked decrease immediately after the eruption. This indicates that during the precursory period the local stress field beneath Mt. Ontake was rotated by stress perturbations caused by the inflation of magmatic/hydrothermal fluids. Post-eruption events of reverse faulting acted to shrink the volcanic edifice after expulsion of volcanic ejecta, controlled by the regional stress field. The misfit angle is a good indicator of the state of volcanic activity. The monitoring method by using this indicator is applicable to other volcanoes and may contribute to the mitigation of volcanic hazards.

  18. Sr isotope diversity of hot spring and volcanic lake waters from Zao volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ishikawa, Hiromasa; Ohba, Tsukasa; Fujimaki, Hirokazu

    2007-09-01

    The ratio of 87Sr/ 86Sr was measured from different water samples of thermal/mineral (hot spring as well as crater lake) and meteoric origins, in order to specify the location and to verify the detailed model of a volcano-hydrothermal system beneath Zao volcano. The ratio showed a trimodal distribution for the case of thermal/mineral water: 0.7052-0.7053 (Type A, Zao hot spring), 0.7039-0.7043 (Type B, Okama crater lake and Shin-funkiko hot spring), and 0.7070-0.7073 (Type C, Gaga, Aone, and Togatta hot springs), respectively. However, in comparison, the ratio was found to be higher for meteoric waters (0.7077-0.7079). The water from the central volcanic edifice (Type B) was found to be similar to that of nearby volcanic rocks in their Sr isotopic ratio. This indicates that the Sr in water was derived from shallow volcanic rocks. The 87Sr/ 86Sr ratio for water from the Zao hot spring (Type A) was intermediate between those of the pre-Tertiary granitic and the Quaternary volcanic rocks, thus suggesting that the water had reacted with both volcanic and granitic rocks. The location of the vapor-liquid separation was determined as the boundary of the pre-Tertiary granitic and the Quaternary volcanic rocks by comparing the results of this strontium isotopic study with those of Kiyosu and Kurahashi [Kiyosu, Y., Kurahashi, M., 1984. Isotopic geochemistry of acid thermal waters and volcanic gases from Zao volcano in Japan. J. Volcanol. Geotherm. Res. 21, 313-331.].

  19. Isotopic geochemistry of acid thermal waters and volcanic gases from Zaō volcano in Japan

    NASA Astrophysics Data System (ADS)

    Kiyosu, Yasuhiro; Kurahashi, Makoto

    1984-08-01

    The chemical composition and D/H, {18O }/{16O } and {34S }/{32S } ratios have been determined for the acid hot waters and volcanic gases discharging from Zaō volcano in Japan. The thermal springs in Zaō volcano issue acid sulfate-chloride type waters (Zaō) and acid sulfate type waters (Kamoshika). Gases emitted at Kamoshika fumaroles are rich in CO 2, SO 2 and N 2, exclusive of H 2O. Chloride concentrations and oxygen isotope data indicate that the Zaō thermal waters issue a fluid mixture from an acid thermal reservoir and meteoric waters from shallow aquifers. The waters in the Zaō volcanic system have slight isotopic shifts from the respective local meteoric values. The isotopic evidence indicates that most of the water in the system is meteoric in origin. Sulfates in Zaō acid sulfate-chloride waters with δ34S values of around +15‰, are enriched in 34S compared to Zaō H 2S, while the acid sulfate waters at Kamoshika contain supergene light sulfate ( δ 34S = ˜ + 4‰ ) derived from volcanic sulfur dioxide from the volcanic exhalations. The sulfur species in Zaō acid waters are lighter in δ34S than those of other volcanic areas, reflecting the difference in total pressure.

  20. Magma Genesis of Sakurajima, the Quaternary post- Aira caldera volcano, southern Kyushu Island, Japan

    NASA Astrophysics Data System (ADS)

    Shibata, T.; Suzuki, J.; Yoshikawa, M.; Kobayashi, T.; Miki, D.; Takemura, K.

    2012-12-01

    Sakurajima volcano is the Quaternary post-caldera volcano of Aira caldera, which was caused by the eruption of huge amount of silicic pyroclastics, situated on Ryukyu arc, southern Kyushu Island, Japan. This volcano is quite active, so it can be considered that the preparation of next caldera-forming eruption with huge amount of silicic magma is proceeding. It is, therefore, expected that the investigation of magma genesis of Sakurajima volcano give us information for the mechanism generating huge amount of silicic magma, which cause the caldera formation. We analyzed major and trace elements with Sr, Nd and Pb isotopic compositions of volcanic rocks from Sakurajima volcano. We sampled (ol) - opx - cpx - pl andesite and dacite from almost all the volcanic units defined by Fukuyama and Ono (1981). In addition to Sakurajima samples, we also studied basaltic rocks erupted at pre-caldera stage of the Aira caldera to estimate the primary magma of Sakurajima volcano. Major and trace element variations generally show linear trends on the Harker diagrams, with the exception of P2O5 and TiO2. Based on the trend of P2O5 vs.SiO2, we divided studied samples low-P (P2O5 < 0.15 wt. %) and high-P (P2O5 > 0.15 wt. %) groups and these groups also display two distinct trends on TiO2-SiO2 diagram. The composition of trace elements shows typical island arc character as depletion of Nb and enrichments of Rb, K and Pb, suggesting addition of aqueous fluids to the mantle wedge. The Zr and Nb concentrations make a liner trend (Zr/Nb = 27) and this trend across from tend of MORB (Zr/Nb = 35) to that of crustal materials (Zr/Nb=17). The Sr, Nd and Pb isotopic compositions broadly plot to on the mixing curve connecting MORB-type mantle and sediments of the Philippine Sea Plate, indicating that the primary magma was generated by partial melting of MORB-type mantle wedge, which was hydrated with fluids derived from the subducted Philippine Sea sediments. But we found that our data plot apart

  1. Crustal deformation of Miyakejima volcano, Japan since the eruption of 2000 using dense GPS campaign observation

    NASA Astrophysics Data System (ADS)

    Fukui, M.; Matsushima, T.; Oikawa, J.; Watanabe, A.; Okuda, T.; Ozawa, T.; Kohno, Y.; Miyagi, Y.

    2013-12-01

    Miyakejima is an active volcanic Island located about 175 km south of Tokyo, Japan. Miyakejima volcano erupted approximately every 20 years in the past 100 years. The latest eruptive activities since 2000 was different from those of the last 100 years, in that the activities included a caldera formation for the first time in 2500 years and gigantic volcanic gas emission that forced islander to evacuate over four and half years. In 2000, a dense GPS observation campaign had detected the magma intrusion in detail (e.g., Irwan et al., 2003; Murase et al., 2006). However, this campaign observation ceased from 2002 to 2010 because a large amount of volcanic gas prevented from entering to the island. Since 2011, we restarted the campaign observation by the dense GPS network, and examined the ongoing magma accumulation process beneath Miyakejima volcano to get insights about the future activity. In this analysis, we combined the data of our campaign observations, the data of the University Union in 2000, and the GEONET data. The observation data were analyzed by RTK-LIB (Takasu et al., 2007) using GPS precise ephemeris from IGS. We estimated the locations and volumes of the pressure sources beneth Miyakejima using an elevation-modified Mogi model (Fukui et al., 2003) and open crack model (Okada, 1992) during the two periods (2000 ~ 2012 and 2011 ~ 2012). We used the software of Magnetic and Geodetic data Computer Analysis Program for Volcano (MaGCAP-V) (Fukui et al., 2010), and estimated the source parameters by trial and error. During 2000 and 2012, a contracting spherical source and contracting dyke were estimated beneath the caldera and at the southwestern part of the island, respectively. In contrast, during 2011 and 2012, an spherical inflation source was estimated a few km beneath the caldera. This result suggest that Miyakejima is now storing new magma for the next eruption. Geospatial Information Authority of Japan (GSI) (2011) suggested that the inflation started

  2. Diffuse degassing survey at the Higashi Izu monogenetic volcano field, Japan

    NASA Astrophysics Data System (ADS)

    Notsu, Kenji; Pérez, Nemesio M.; Fujii, Naoyuki; Hernández, Pedro A.; Mori, Toshiya; Padrón, Eleazar; Melián, Gladys

    2016-04-01

    The Higashi-Izu monogenetic volcanic group, which consists of more than 60 volcanoes, overlies the polygenetic volcanoes in the eastern part of the Izu peninsula, Japan, which are distributed over the area of 350 km2. Some of the monogenetic volcanoes are located on northwest-southeast alignments, suggesting that they developed along fissures. Recent volcanic activity occurred offshore, e.g., at the Izu-Oshima volcano, which erupted in 1986 and a submarine eruption of the small new Teishi knoll off eastern Izu Peninsula in 1989 (Hasebe et al., 2001). This study was carried out to investigate the possible relationship of diffuse CO2 emission and the recent seismic activity recorded NE of Higashi Izu monogenetic volcanic field, to quantify the rate at which CO2 is diffusely degassed from the studied area including Omuroyama volcano and to identify the structures controlling the degassing process. Measurements were carried out over a three day period from 8-10 July 2013. Diffuse CO2 emission surveys were always carried out following the accumulation chamber method and spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. Soil gas samples were collected at 30-40 cm depth by withdrawal into 60 cc hypodermic syringes to characterize the chemical and isotopic composition of the soil gas. At Omurayama volcano, soil CO2 efflux values ranged from non-detectable to 97.5 g m‑2 d‑1, while at the seismic swarm zone ranged from 1.5 to 233.2 g m‑2 d‑1 and at the fault zone ranged from 5.7 to 101.2 g m‑2 d‑1. Probability-plot technique of all CO2 efflux data showed two different populations, background with a mean of 8.7 g m‑2 d‑1 and peak with a mean of 92.7 g m‑2 d‑1. In order to strength the deep seated contribution to the soil gases at the studied are, carbon isotopic analysis were performed in the CO2 gas. Soil gases (He, CO2 and N2) showed a clear mixing trend between air composition and a rich CO2 end

  3. Vertical movements of the Murono mud volcano in Japan caused by the Naganoken Kamishiro Fault Earthquake in 2014

    NASA Astrophysics Data System (ADS)

    Kusumoto, Shigekazu; Hamamoto, Toshiki; Fukuda, Yoichi; Takahashi, Atsushi

    2015-04-01

    We observed vertical movements of the Murono mud volcano, Niigata, Japan, caused by the Naganoken Kamishiro Fault Earthquake ( M = 6.7) on 22 November 2014. Precise levelling around the mud volcano was carried out on 27 November 2014, and the obtained elevation was compared with the data obtained for 11 November 2014. It was found that an elliptical uplift area, about 46 mm in magnitude and an order of magnitude smaller than that of the ones formed due to the past movements caused by the earthquakes in the same area, had been formed. It was considered that the structures of the shallow subsurface as well as the distance between the mud volcano and epicentre might play an important role in understanding the magnitude of vertical movements and distribution patterns.

  4. Diffuse carbon dioxide emissions from hidden subsurface structures at Asama volcano, Japan

    NASA Astrophysics Data System (ADS)

    Morita, Masaaki; Mori, Toshiya; Kazahaya, Ryunosuke; Tsuji, Hiroshi

    2016-03-01

    We measured diffuse carbon dioxide (CO2) flux and soil temperature around the summit of Asama volcano, Japan to assess the diffuse degassing structure around the summit area. Soil CO2 flux was measured using an accumulation chamber method, and the spatial distributions of CO2 flux and soil temperature were derived from the mean of 100 sequential Gaussian simulations. Results show that soil CO2 flux was high on the eastern flank of Kamayama cone and the eastern rim of Maekake crater, the outer cone. These areas mostly correspond to high-temperature anomalies. The average emission rate of diffuse CO2 was calculated to be 12.6 t day-1 (12.2-14.6 t day-1). Such diffuse emissions account for 12 % of the total (diffuse and plume) CO2 emissions from the summit area. The diffuse CO2 anomalies probably reflect permeable zones controlled by local topography and hidden fractures bordering Maekake crater. The permeable zones are connected to the low-electrical-resistivity zone inferred to indicate both a hydrothermal fluid layer and an upper sealed layer made of clay minerals. Magmatic gas from the main conduit ascends to the volcano surface through this fluid layer and the permeable zones. These insights emphasize that the pathways and the connection between the pathways and the source of diffuse CO2 combine to create the pattern of heterogeneous diffuse CO2 emission seen at the surface. Only by using a combination of gas measurements and geophysical tools can we begin to understand the dynamics of this system as a whole.

  5. Multi-parametric Observation of Volcanic Lightning at Sakurajima Volcano, Japan.

    NASA Astrophysics Data System (ADS)

    Cimarelli, C.; Alatorre-Ibarguengoitia, M.; Aizawa, K.; Yokoo, A.; Dingwell, D. B.

    2014-12-01

    Ash-rich volcanic plumes are very often associated with electrical discharges producing majestic display of lightning. Observation and understanding of this phenomenon can shed light on crucial properties of the plume such as mass eruption rate and content of fine particles, as recently demonstrated by laboratory investigation of volcanic lightning (Cimarelli et al., 2014). Despite the recent advances in experimental investigations and the increasing detailed observation by lightning monitoring arrays, many fundamental questions are yet unsolved. In particular, to which extent electrical discharges in volcanic plumes are comparable to thundercloud lightning? Is the presence of hydrometeors in the plume a necessary condition for the generation of volcanic lightning? Multiparametric observation of electrical activity at erupting volcanoes is key to answering these questions. Here we present the results of a campaign of measurements conducted at Sakurajima volcano (southern Japan) where, for the first time, we combined synchronized high-speed imaging with magnetotelluric (MT) and acoustic measurements of ash-rich plumes generating electrical discharges and compare our observations with maximum plume height measurement and atmospheric soundings. Results show that flashes concentrate within the plume and closer to the crater. Good correlation if found between cloud-to-ground versus intra-cloud events and the frequency and duration of recorded MT-signals, while measured currents at Sakurajima are 10 to 100 times smaller than those produced by thundercloud discharges. Finally, atmospheric soundings show that plumes producing flashes didn't cross isotherms relevant for ice formation thus discarding a relevant contribution of hydrometeors in the generation of the observed volcanic lightning. Cimarelli et al. 2014. Experimenal generation of volcanic lightning. Geology v. 42, no. 1 doi: 10.1130/G34802.1

  6. A Brownian model for recurrent volcanic eruptions: an application to Miyakejima volcano (Japan)

    NASA Astrophysics Data System (ADS)

    Garcia-Aristizabal, Alexander; Marzocchi, Warner; Fujita, Eisuke

    2012-03-01

    The definition of probabilistic models as mathematical structures to describe the response of a volcanic system is a plausible approach to characterize the temporal behavior of volcanic eruptions and constitutes a tool for long-term eruption forecasting. This kind of approach is motivated by the fact that volcanoes are complex systems in which a completely deterministic description of the processes preceding eruptions is practically impossible. To describe recurrent eruptive activity, we apply a physically motivated probabilistic model based on the characteristics of the Brownian passage-time (BPT) distribution; the physical process defining this model can be described by the steady rise of a state variable from a ground state to a failure threshold; adding Brownian perturbations to the steady loading produces a stochastic load-state process (a Brownian relaxation oscillator) in which an eruption relaxes the load state to begin a new eruptive cycle. The Brownian relaxation oscillator and Brownian passage-time distribution connect together physical notions of unobservable loading and failure processes of a point process with observable response statistics. The Brownian passage-time model is parameterized by the mean rate of event occurrence, μ, and the aperiodicity about the mean, α. We apply this model to analyze the eruptive history of Miyakejima volcano, Japan, finding a value of 44.2 (±6.5 years) for the μ parameter and 0.51 (±0.01) for the (dimensionless) α parameter. The comparison with other models often used in volcanological literature shows that this physically motivated model may be a good descriptor of volcanic systems that produce eruptions with a characteristic size. BPT is clearly superior to the Exponential distribution, and the fit to the data is comparable to other two-parameters models. Nonetheless, being a physically motivated model, it provides an insight into the macro-mechanical processes driving the system.

  7. Sulfur dioxide emissions related to volcanic activity at Asama volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ohwada, Michiko; Kazahaya, Kohei; Mori, Toshiya; Kazahaya, Ryunosuke; Hirabayashi, Jun-ichi; Miyashita, Makoto; Onizawa, Shin'ya; Mori, Takehiko

    2013-12-01

    A 40-year-long record of the sulfur dioxide (SO2) emission rate of Asama volcano, Japan, is presented including high-temporal-resolution data since the 2004 eruption. The 2004 and 2008-2009 eruptive activities were associated with high SO2 emission, and SO2 emission rates markedly fluctuated. In contrast, stable and weak SO2 emissions have been observed for the rest of the investigated interval. The fluctuation of the SO2 emission rates is correlated with the number of shallow low-frequency B-type earthquakes, implying that increased flows of gas and/or magma induced the B-type earthquakes along the shallow conduit. The total volumes of outgassed magma during the 2004 and 2008-2009 eruptive activities are estimated to be 1.9 × 108 and 1.5 × 108 m3, respectively. These volumes are about 100-200 times larger than those of the erupted magma, indicating that the large volumes of the magma were outgassed without being erupted (i.e., excess degassing/outgassing). Degassing and outgassing driven by magma convection rather than by permeable gas flow in the conduit is concluded as the probable degassing/outgassing process of Asama volcano based on model examinations, and is thought to occur regardless of the outgassing intensity. Production rates of outgassed magma related to the 2004 and 2008-2009 eruptive periods are estimated to have been 7.4 × 103 and 6.7 × 103 kg/s, respectively. These values are one order of magnitude higher than the average production rate of 0.92 × 103 kg/s for the inactive periods. Increased supply of fresh magma is thought to activate magma convection in the conduit and to thereby increase magma degassing/outgassing.

  8. Observations of eruption clouds from Sakura-zima volcano, Kyushu, Japan from Skylab 4

    USGS Publications Warehouse

    Friedman, J.D.; Heiken, G.; Randerson, D.; McKay, D.S.

    1976-01-01

    Hasselblad and Nikon stereographic photographs taken from Skylab between 9 June 1973 and 1 February 1974 give synoptic plan views of several entire eruption clouds emanating from Sakura-zima volcano in Kagoshima Bay, Kyushu, Japan. Analytical plots of these stereographic pairs, studied in combination with meteorological data, indicate that the eruption clouds did not penetrate the tropopause and thus did not create a stratospheric dust veil of long residence time. A horizontal eddy diffusivity of the order of 106 cm2 s-1 and a vertical eddy diffusivity of the order of 105 cm2 s-1 were calculated from the observed plume dimensions and from available meteorological data. These observations are the first, direct evidence that explosive eruption at an estimated energy level of about 1018 ergs per paroxysm may be too small under atmospheric conditions similar to those prevailing over Sakura-zima for volcanic effluents to penetrate low-level tropospheric temperature inversions and, consequently, the tropopause over northern middle latitudes. Maximum elevation of the volcanic clouds was determined to be 3.4 km. The cumulative thermal energy release in the rise of volcanic plumes for 385 observed explosive eruptions was estimated to be 1020 to 1021 ergs (1013 to 1014 J), but the entire thermal energy release associated with pyroclastic activity may be of the order of 2.5 ?? 1022 ergs (2.5 ?? 1015 J). Estimation of the kinetic energy component of explosive eruptions via satellite observation and meteorological consideration of eruption clouds is thus useful in volcanology as an alternative technique to confirm the kinetic energy estimates made by ground-based geological and geophysical methods, and to aid in construction of physical models of potential and historical tephra-fallout sectors with implications for volcano-hazard prediction. ?? 1976.

  9. Stratigraphy, grain-size and component characteristics of the 2011 Shinmoedake eruption deposits, Kirishima Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Miyabuchi, Yasuo; Hanada, Daisuke; Niimi, Hiroshi; Kobayashi, Tetsuo

    2013-05-01

    The 2011 eruption of Shinmoedake Volcano, part of Kirishima Volcanic Complex in southern Kyushu, southwestern Japan was characterized by a significant change in eruption style from subplinian eruptions to lava effusion in the summit crater, and subsequent vulcanian eruptions. The stratigraphy, distribution and textures of fallout tephra deposits reveal the character and sequence of the eruption. The tephra-fall deposits distributed southeast of the volcano are divided into five units based on the eruptive events. Unit 1 is a lithic-rich fine ash-fall deposited on 19 January 2011. Unit 2 is a very well to well sorted pumice-fall deposit from the evening of January 26 to early morning of January 27, and is the main product of the 2011 eruption. The unit-2 deposit was dispersed throughout an area extending more than 20 km SE of the source crater. Unit 3 comprises tephra-fall deposits related to the January 27 15 h 41 min explosion, and is subdivided into lower (3L) and upper (3U) parts. Unit 3L is a lithic-rich well-sorted coarse ash-fall, deposited during the initial stage of the January 27 15 h 41 min eruption, whereas the unit 3U is composed mainly of coarse-grained pumiceous lapilli. Unit 4 is a fine ash-fall deposited on January 28-29, and consists mostly of fresh lava fragments and crystal grains. Unit 5 is a product of the largest vulcanian eruption, on March 13. Unit-5 tephra is a lithic-rich medium to coarse ash-fall deposit. Furthermore, the 31 August 2011 ash-fall deposit extending 19 km southwest of the Shinmoedake crater is fine grained and contains abundant lava fragments. Temporal variations in grain size and components of the 2011 eruption deposits reveal the eruption sequence and the conditions of the crater, conduit and magma chamber.

  10. Characterizing magma storage at Aira caldera and Sakurajima volcano (Japan) from geodetic inversions

    NASA Astrophysics Data System (ADS)

    Hickey, J.; Gottsmann, J.; Iguchi, M.; Nakamichi, H.

    2014-12-01

    Aira caldera is located within Kagoshima Bay at the southern end of Kyushu, in Japan. Sakurajima, a post-caldera andesitic stratovolcano, sits on the calderas southern rim and is Japan's most active volcano. Historical records of activity at Sakurajima are punctuated with larger events: for example, in 1914 a major flank eruption ejected 0.52 km3 of pumice and ash, and 1.34 km3 of lava. The co-eruptive subsidence accompanying this eruption was around one metre in the vertical component, as determined from leveling surveys. Repeat surveys, and the addition of modern GPS data indicate that the present day level of ground uplift is approaching the level inferred before the 1914 eruption. This study is focused on interpreting the current deformation with integration of additional geophysical signals to constrain the subsurface magma storage conditions. Analytical geodetic models have been previously used to infer a deep spherical reservoir beneath Aira caldera and a smaller source beneath the summit craters of Sakurajima. However, subsequent geophysical explorations have shown that the assumptions inherent in these simple models may not apply. We use the Finite Element method to model the recorded deformation with an inverse least-squares approach. Our models incorporate the surrounding topography/bathymetry and three-dimensional medium heterogeneities inferred from seismic tomography. These are used to assess their respective significance when solving for the optimum source location. Subsequent forward Finite Element models quantify the importance of rheology and thermo-mechanical coupling owing to the observed high seismic attenuation and aseismic zones. The results are evaluated alongside the current volcanic activity to yield new insights into the behaviour of the Aira-Sakurajima sub-volcanic system.

  11. Constraining tephra dispersion and deposition from three subplinian explosions in 2011 at Shinmoedake volcano, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Maeno, Fukashi; Nagai, Masashi; Nakada, Setsuya; Burden, Rose E.; Engwell, Samantha; Suzuki, Yuki; Kaneko, Takayuki

    2014-06-01

    Constraining physical parameters of tephra dispersion and deposition from explosive volcanic eruptions is a significant challenge, because of both the complexity of the relationship between tephra distribution and distance from the vent and the difficulties associated with direct and comprehensive real-time observations. Three andesitic subplinian explosions in January 2011 at Shinmoedake volcano, Japan, are used as a case study to validate selected empirical and theoretical models using observations and field data. Tephra volumes are estimated using relationships between dispersal area and tephra thickness or mass/area. A new cubic B-spline interpolation method is also examined. Magma discharge rate is estimated using theoretical plume models incorporating the effect of wind. Results are consistent with observed plume heights (6.4-7.3 km above the vent) and eruption durations. Estimated tephra volumes were 15-34 × 106 m3 for explosions on the afternoon of 26 January and morning of 27 January, and 5.0-7.6 × 106 m3 for the afternoon of 27 January; magma discharge rates were in the range 1-2 × 106 kg/s for all three explosions. Clast dispersal models estimated plume height at 7.1 ± 1 km above the vent for each explosion. The three subplinian explosions occurred with approximately 12-h reposes and had similar mass discharge rates and plume heights but decreasing erupted magma volumes and durations.

  12. ASTER-SRTM Perspective of Mount Oyama Volcano, Miyake-Jima Island, Japan

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Mount Oyama is a 820-meter-high (2,700 feet) volcano on the island of Miyake-Jima, Japan. In late June 2000, a series of earthquakes alerted scientists to possible volcanic activity. On June 27, authorities evacuated 2,600 people, and on July 8 the volcano began erupting and erupted five times over that week. The dark gray blanket covering green vegetation in the image is the ash deposited by prevailing northeasterly winds between July 8 and 17. This island is about 180 kilometers (110 miles) south of Tokyo and is part of the Izu chain of volcanic islands that runs south from the main Japanese island of Honshu. Miyake-Jima is home to 3,800 people. The previous major eruptions of Mount Oyama occurred in 1983 and 1962, when lava flows destroyed hundreds of houses. An earlier eruption in 1940 killed 11 people.

    This image is a perspective view created by combining image data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA's Terra satellite with an elevation model from the Shuttle Radar Topography Mission (SRTM). Vertical relief is exaggerated, and the image includes cosmetic adjustments to clouds and image color to enhance clarity of terrain features.

    The ASTER instrument is a cooperative project between NASA, JPL, and the Japanese Ministry of International Trade and Industry.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the

  13. Variation of Volcanic Gas Composition at a Persistently Degassing Asama Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Shinohara, H.; Ohminato, T.; Takeo, M.

    2013-12-01

    Asama volcano at central Japan is a persistently degassing andesitic volcano and repeated eruptions every several years. The recent eruptions occurred in September 2004, August 2008 and February 2009 and are followed by increase of the volcanic gas emission during several months. The SO2 flux is typically 1,000-4,000 t/d during the high flux period after the eruption, whereas the flux is around 100 t/d during the low gas flux periods (JMA, 2013; Ohwada et al., in review). This study aims to understand the controlling process of volcano degassing based on the volcanic gas composition data. In particular, we focus to evaluate the gas composition contrast between the high and low gas flux periods. As the fumaroles and degassing vent locate in the summit crater of 500-m-diamter and are inaccessible, we estimated the gas composition by plume measurements with the Multi-GAS at the crater rim. The HCl/SO2 ratios are obtained by the alkali-filter trap. We started the repeat Multi-GAS measurements in 2004 and installed an automatic Multi-GAS monitoring station for a daily measurement at the western rim of the summit crater in 2010. The gas compositions obtained by the Multi-GAS measurements are often scattered even during the day of measurements, in particular during the low flux period and the scatter is likely due to variable contamination of gases from low-temperature fumaroles locating along the crater rim because the low-temperature fumaroles locate closer to the measurement site that the major degassing vent at the bottom of the crater. If we plot the gas concentration ratio, such as CO2/SO2 against SO2 concentration, the ratio commonly converges to a certain value at high SO2 concentration and this ratio is considered as representative of the major gas emission. The estimated molar ratios are CO2/SO2=1×0.5, HCl/SO2=0.2×0.1 and H2O/SO2=60×30 without clear contrast during the high and low flux periods. The CO2/SO2 ratios obtained based on a single day data tend to

  14. Estimated pressure source on Kozu Island volcano, South Central Japan, from GPS measurements (July 1996-August 1999)

    NASA Astrophysics Data System (ADS)

    Kimata, Fumiaki; Kariya, Shin-ichi; Fujita, Masayuki; Matsumoto, Kunio; Tabei, Takao; Segawa, Jiro; Yamada, Akiko

    2000-11-01

    Although the Kozu Island Volcano, one of the Izu Islands Volcanoes in the south part Central Japan, is an active volcano, there is no record of the eruption for about 1100 years since the last eruption in 833 A.D. Since 1988, frequent earthquake swarms are observed around the Kozu Island, and the uplift of 2-4 cm/yr is observed on the island by tidal observations. Station velocities detected by GPS measurements since 1989 show velocities that differ from the convergent velocity of the Philippine Sea plate calculated from plate motion models. A local GPS network with 12 stations is occupied around the volcano, and the GPS measurements are repeated every about six month since July 1996. Inflated deformation of 2-4 cm/yr are detected from the GPS measurements and the pressure source is estimated to be located in the northeastern part of the island at a depth of 2.1 km using Mogi solution. Negative gravity changes of more than 30 microgal are also measured above the pressure source in the period November 1998 to July 1999, consistent with uplift.

  15. Detection of Aeromagnetic Field Changes Using an Unmanned Autonomous Helicopter: Repeated Experiments at Tarumae Volcano (Japan)

    NASA Astrophysics Data System (ADS)

    Hashimoto, T.; Koyama, T.; Yanagisawa, T.; Yoshimoto, M.; Ohminato, T.; Kaneko, T.

    2015-12-01

    Volcanic eruptions often prohibit humans from approaching active craters. Meanwhile, it is important, especially at the initial stage of an eruption, to perform visual surveillance, geophysical/chemical measurements and material sampling in the vicinity of the craters. Besides scientific purposes, information from such surveys is helpful for the local government in deciding the response to volcanic unrest. We started airborne surveys using an unmanned helicopter on a trial basis in cooperation with the Hokkaido Regional Development Bureau. As a part of the project, we repeated aeromagnetic surveys over Mt. Tarumae (1,041m), one of the active volcanoes in northern Japan in 2011, 2012 and 2013. Owing to its high accuracy of positioning control in the autonomous flight with the aid of GPS navigation and the fairly small magnetic field gradient in the air, temporal changes up to 30 nT were successfully detected through a direct comparison between separate surveys. The field changes in the air were mostly consistent with those on the ground surface, which suggested remagnetization due to cooling beneath the summit lava dome. Through our three-year experiments, the unmanned helicopter was proved to be useful for aeromagnetic monitoring. Although the system still has some limitations in terms of maximum flight altitude and operational range from the base station, we emphasize the following three advantages of this technique. (1) Operation without exposing human to volcanic hazards. (2) Straightforward data processing procedure to obtain temporal magnetic field changes, which is especially important in an emergency response such as an ongoing unrest. (3) Great reduction of the cost to maintain ground-based monitoring stations for many years. Acknowledgments: We express sincere thanks to Muroran and Sapporo Development and Construction Departments of the HRDB for the cooperation in the field experiments using their unmanned helicopter.

  16. Application of terrestrial laser scanning for detection of ground surface deformation in small mud volcano (Murono, Japan)

    NASA Astrophysics Data System (ADS)

    Hayakawa, Yuichi S.; Kusumoto, Shigekazu; Matta, Nobuhisa

    2016-07-01

    We perform terrestrial laser scanning (TLS) to detect changes in surface morphology of a mud volcano in Murono, north-central Japan. The study site underwent significant deformation by a strong earthquake in 2011, and the surface deformation has continued in the following years. The point cloud datasets were obtained by TLS at three different times in 2011, 2013 and 2014. Those point clouds were aligned by cloud-based registration, which minimizes the closest point distance of point clouds of unchanged ground features, and the TLS-based point cloud data appear to be suitable for detecting centimeter-order deformations in the central domain of the mud volcano, as well as for measurements of topographic features including cracks of paved ground surface. The spatial patterns and accumulative amount of the vertical deformation during 2011-2014 captured by TLS correspond well with those previously reported based on point-based leveling surveys, supporting the validity of TLS survey.

  17. Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan

    PubMed Central

    Uyeda, S.; Hayakawa, M.; Nagao, T.; Molchanov, O.; Hattori, K.; Orihara, Y.; Gotoh, K.; Akinaga, Y.; Tanaka, H.

    2002-01-01

    Significant anomalous changes in the ultra low frequency range (≈0.01 Hz) were observed in both geoelectric and geomagnetic fields before the major volcano-seismic activity in the Izu Island region, Japan. The spectral intensity of the geoelectric potential difference between some electrodes on Niijima Island and the third principal component of geomagnetic field variations at an array network in Izu Peninsula started to increase from a few months before the onset of the volcano-seismic activity, culminating immediately before nearby magnitude 6 class earthquakes. Appearance of similar changes in two different measurements conducted at two far apart sites seems to provide information supporting the reality of preseismic electromagnetic signals. PMID:12032286

  18. Intensive hydration of the wedge mantle at the Kuril arc - NE Japan arc junction: implications from mafic lavas from Usu Volcano, northern Japan

    NASA Astrophysics Data System (ADS)

    Kuritani, T.; Tanaka, M.; Yokoyama, T.; Nakagawa, M.; Matsumoto, A.

    2015-12-01

    The southwestern part of Hokkaido, northern Japan, is located at the junction of the NE Japan arc and the Kuril arc. The subducting Pacific plate under this region shows a hinge-like shape due to the dip change of the subducting plate along the trench. Because of the interest in this unique tectonic setting, this arc-arc junction has been the focus of extensive geophysical studies (e.g. Kita et al., 2010, Morishige and van Keken, 2014; Wada et al., 2015). This region is also known as an area in which magmatism has been intense; there are many active volcanoes such as Usu, Tarumae, and Komagatake, and large calderas including Toya, Shikotsu, and Kuttara. In this region, the temporal and spatial evolution of the volcanism and the chemical compositions of the volcanic rocks are well characterized (e.g. Nakagawa, 1992). However, the generation conditions of magmas have not been estimated for these volcanoes, probably because of the scarcity of basaltic products. Therefore, a possible link between the tectonic setting and the intense magmatism is still unclear. In this study, we carried out a petrological and geochemical study on mafic lavas (49.6-51.3 wt.% SiO2) from Usu Volcano, and estimated the conditions under which the magmas were generated. By application of a plagioclase-melt hygrometer to the plagioclase and the host magma, the water content of ~6.5 wt.% was obtained for the basaltic magma. Using this information, as well as the olivine maximum fractionation model (Tatsumi et al., 1983), the composition of the primary magma is estimated to be 47.9 wt.% SiO2, 15.1 wt.% MgO, and 4.1 wt.% H2O. Analyses using the multi-component thermodynamics suggest that the primary magma was generated in the source mantle with 0.9 wt.% H2O at 1310ºC and at 1.6 GPa. The water content of 0.9 wt.% of the source mantle is significantly higher than the estimates for the source mantle in the main NE Japan arc (<0.7 wt.% H2O); this implies that the flux of slab-derived fluids is

  19. The effect of porosity and crystallinity on magma rheology at Unzen volcano, Japan

    NASA Astrophysics Data System (ADS)

    Coats, Rebecca; Lavallée, Yan; Kendrick, Jackie E.; Wallace, Paul A.; Ashworth, James D.; Hornby, Adrian; Miwa, Takahiro

    2016-04-01

    Eruptions of lava domes are some of the most unpredictable and dangerous volcanic phenomena, and their frequent occurrence highlights the priority of improving our understanding of the mechanisms at play during magma ascent. For example, between 1991 and 1995 Mt. Unzen sustained an extensive period of dome growth. During this time approximately 2.1x108 m3 dense rock equivalent of magma was emplaced at effusion rates of 0.1-4x105 m3d‑1. Repeated partial collapses of the dome generated frequent pyroclastic density currents which caused several fatalities and damage to populated areas near Shimabara City. One of the keys to grasping the switch between effusive to explosive behaviour, as well as the onset of a dome collapse event lies within understanding the rheological behaviour of upwelling magma. Although the conditions which lead to failure of magma are now increasingly studied, we lack an understanding of the influence of mechanisms at play during magma deformation. Strain rate and temperature play primary roles in the transition of silicate melts from viscous bodies to elastic solids; this regime change is known as the viscous-brittle transition and is bound by the glass transition of the interstitial melt, which signals the beginning of either fracture or flow. Crystals and pores present in the system can alter the position of the viscous-brittle transition. Laboratory experiments which aim to simulate realistic volcanic conditions permit the controlled study of volcanic processes, and help determine the behaviour of multi-phase magmatic suspensions. For magma with high crystal contents (>40%) rheology is strongly influenced by the crystalline phase and is strain rate dependent. Here we present the results of high-temperature deformation experiments on variably porous (9-33%), crystal-rich (>50%) dacite lavas from Unzen volcano, Japan. Uniaxial compression tests were carried out on dacitic samples from Unzen at room temperature (˜20° C) and high temperature

  20. Volcano Observations Using an Unmanned Autonomous Helicopter : seismic and GPS observations near the active summit area of Sakurajima and Kirishima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ohminato, T.; Kaneko, T.; Koyama, T.; Watanabe, A.; Takeo, M.; Iguchi, M.; Honda, Y.

    2012-04-01

    Observations in the vicinity of summit area of active volcanoes are very important from various viewpoints such as understanding physical processes in the volcanic conduit. It is, however, highly difficult to install observation sensors near active vents because of the risk of sudden eruptions. We have been developing a safe volcano observation system based on an unmanned aerial vehicle (UAV). As an UAV, we adopted an unmanned autonomous helicopter manufactured by Yamaha-Motor Co., Ltd. We have also developed earthquake observation modules and GPS receiver modules that are exclusively designed for UAV installation at summit areas of active volcanoes. These modules are light weight, compact size, and solar powered. For data transmission, a commercial cellular-phone network is used. Our first application of the sensor installation by the UAV is Sakurajima, one of the most active volcanos in Japan. In November 2009, 2010, and 2011, we installed up to four seismic sensors within 2km from the active summit crater. In the 2010 and 2011 operations, we succeeded in pulling up and collecting the sensor modules by using the UAV. In the 2011 experiment, we installed two GPS receivers near the summit area of Sakurajima volcano. We also applied the UAV installation to another active volcano, Shinmoedake in Kirishima volcano group. Since the sub-plinian eruption in February 2011, entering the area 3km from the summit of Shinmoe-dake has been prohibited. In May and November 2011, we installed seismic sensors and GPS receivers in the off-limit zone. Although the ground coupling of the seismic modules is not perfect due to the way they are installed, the signal-to-noise ratio of the seismic signals recorded by these modules is fairly good. Despite the low antenna height of 50 cm from the ground surface, the location errors in horizontal and vertical GPS components are 1cm and 3cm, respectively. For seismic signals associated with eruptions at Sakurajima from November 2010 to

  1. Evolution of magma feeding system in Kumanodake agglutinate activity, Zao Volcano, northeastern Japan

    NASA Astrophysics Data System (ADS)

    Takebe, Yoshinori; Ban, Masao

    2015-10-01

    The Kumanodake agglutinate of Zao Volcano in northeastern Japan consists of pyroclastic surge layers accumulated during the early part of the newest stage of activity (ca. 33 ka to present). Our petrologic study of this agglutinate based on systematically collected samples aims to reveal the evolution of magma feeding system. To understand the magma evolution, we have examined samples from the agglutinate by using petrologic data including, petrography, analysis of minerals (plagioclase, pyroxene, and olivine), glass compositions, and whole rock major element and trace element (Ba, Sr, Cr, Ni, V, Rb, Zr, Nb, and Y) compositions. Agglutinate are mixed, medium-K, calc-alkaline olv-cpx-opx basaltic andesite (55.2-56.2% SiO2). Results show that the magma feeding system comprised a shallow felsic chamber injected by mafic magma from depth. The felsic magma (59-62% SiO2, 950-990 °C), which was stored at a shallower depth, had orthopyroxene (Mg# = 60-69), clinopyroxene (Mg# = 65-71), and low-An plagioclase (Anca. 58-70). The mafic magma is further divisible into two types: less-differentiated and more-differentiated, designed respectively as an initial mafic magma-1 and a second mafic magma-2. The original mafic magma-1 was olivine (Fo~ 84) basalt (ca. 48-51% SiO2, 1110-1140 °C). The second mafic magma-2, stored occasionally at 4-6 km depth, was basalt (1070-1110 °C) having Foca. 80 olivine and high-An (Anca. 90) plagioclase phenocrysts. These two magmas mixed (first mixing) to form hybrid mafic magma. The forced injections of the hybrid mafic magmas activated the felsic magma, and these two were mixed (second mixing) shortly before eruptions. The explosivity is inferred to have increased over time because the abundance of large scoria increased. Furthermore, the erupted magma composition became more mafic, which reflects increased percentage of the hybrid mafic magma involved in the second mixing. At the beginning of activity, the mafic magma also acted as a heat

  2. Physical properties of volcanic lightning: Constraints from magnetotelluric and video observations at Sakurajima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Aizawa, Koki; Cimarelli, Corrado; Alatorre-Ibargüengoitia, Miguel A.; Yokoo, Akihiko; Dingwell, Donald B.; Iguchi, Masato

    2016-06-01

    The lightning generated by explosive volcanic eruptions is of interest not only as a promising technique for monitoring volcanic activity, but also for its broader implications and possible role in the origin of life on Earth, and its impact on the atmosphere and biosphere of the planet. However, at present the genetic mechanisms and physical properties of volcanic lightning remain poorly understood, as compared to our understanding of thundercloud lightning. Here, we present joint magnetotelluric (MT) data and video imagery that were used to investigate the physical properties of electrical discharges generated during explosive activity at Sakurajima volcano, Japan, and we compare these data with the characteristics of thundercloud lightning. Using two weeks of high-sensitivity, high-sample-rate MT data recorded in 2013, we detected weak electromagnetic signals radiated by volcanic lightning close to the crater. By carefully inspecting all MT waveforms that synchronized with visible flashes, and comparing with high-speed (3000 frame/s) and normal-speed (30 frame/s) videos, we identified two types of discharges. The first type consists of impulses (Type A) and is interpreted as cloud-to-ground (CG) lightning. The second type is characterized by weak electromagnetic variations with multiple peaks (Type B), and is interpreted as intra-cloud (IC) lightning. In addition, we observed a hybrid MT event wherein a continuous weak current accompanied Type A discharge. The observed features of volcanic lightning are similar to thunderstorm lightning, and the physical characteristics show that volcanic lightning can be treated as a miniature version of thunderstorm lightning in many respects. The overall duration, length, inter-stroke interval, peak current, and charge transfer all exhibit values 1-2 orders of magnitude smaller than those of thunderstorm lightning, thus suggesting a scaling relation between volcanic and thunderstorm lightning parameters that is independent of

  3. Uplift revealed by LASER scanner surveys in Murono mud volcano, Niigata Prefecture, Japan, and estimation of its source

    NASA Astrophysics Data System (ADS)

    Takahashi, A.; Fukuda, Y.; Kusumoto, S.

    2014-12-01

    Since mud volcanoes spew out pressurized material, such as natural gas, oil, mud including water from a deeper ground, the activities of the mud volcanoes are good indicators of the stress conditions/orientations as well as the tectonic controls. The Murono mud volcano area located in Tokamachi City, Niigata prefecture, Japan, is one of the active ground deforming areas associated with mud, natural gas, oil and water eruptions. This area is famous because rapid ground deformation events were recorded corresponding to neighboring large earthquakes. For instance, associated with Naganoken-Hokubu Earthquake (Mw. 6.7) which occurred in 2011, the area recorded a sudden large uplift of about 50 cm. In order to reveal the source mechanism of the mud volcano, Toyama University has been conducting successive leveling surveys at 61 benchmarks. They revealed that the same area of the rapid uplift of 2011 has been still uplifting, even the amount of the uplift is much smaller (20 mm/yr). However, the source of the uplift could not be well identified due to the low spatial resolutions. Therefore, in order to obtain a high resolution land deformation pattern, we have conducted laser scanning surveys two times in June and October 2013, using TOPCON Imaging Station IS-301, which can obtain 3D point cloud data by the automatic laser scanning mode without reflector. The surface deformations obtained by comparing the June and October datasets indicate clear uplifts where the sudden uplift occurred. Since the uplift area show a clear concentric pattern, we estimated the source of the uplift assuming a Mogi source model. The obtained source parameters are, depth=14[m], Volume=14[m3], assuming the Poisson's ratio of 0.25. Then the calculated uplift at the nearest benchmark also shows good agreement with the uplift obtained by the leveling survey. The current uplift is much smaller than the 2011 uplift. Nevertheless both sources could be the same, because the areas of the uplifts are

  4. Precursory tilt changes of small phreatic eruptions of Meakan-dake volcano, Hokkaido, Japan, in November 2008

    NASA Astrophysics Data System (ADS)

    Aoyama, Hiroshi; Oshima, Hiromitsu

    2015-07-01

    Although forecasting an occurrence of phreatic eruption is very difficult, it has been reported that some precursory activities often precede these eruptions at several volcanoes. In this study, we observed seismic activities before and during the 2008 phreatic eruption at Meakan-dake volcano, eastern Hokkaido, Japan, by using broadband seismometers and surface mount-type tiltmeters. The precursory increase in seismicity began in late September about 2 months before the first eruption on November 18. After several rises and falls in seismicity in October and in early November, a small volcanic tremor was observed early on November 16. Although the original velocity seismogram of the tremor generally appeared to be spindle shaped, an outstanding ramp function appeared in the displacement seismogram obtained by simple integration. Since the ramp function appeared only in the horizontal components and continued for about 3 min, which is sufficiently longer than the natural period of the seismometer, we regarded the ramp function as an expression of the tilting motions of seismic stations that was quantitatively confirmed by the strong similarity between horizontal displacement seismograms and tilt data from co-located biaxial tiltmeter. Azimuthal distribution of three tilting vectors obtained from broadband seismograms was not consistent with a simple spherical source but rather strongly suggested a vertical dike under the crater. In this study, we confirmed that an almost vertical single dike effectively explains the observed tilting vectors. The estimated volume increase in the dike was 4-5 × 104 m3. The strike direction of the dike is highly consistent with the alignment of the hydrothermal area on and around the volcano. Our dike model also partially explains the changes in global navigation satellite system (GNSS) measurement and in groundwater levels reported in previous research. Since a similar deformation coincided with a volcanic tremor preceding the 2006

  5. Relationship between geomorphology and lithotypes of lahar deposit from Chokai volcano, Japan

    NASA Astrophysics Data System (ADS)

    Minami, Y.; Ohba, T.; Hayashi, S.; Kataoka, K.

    2013-12-01

    Chokai volcano, located in the northern Honshu arc in Japan, is an andesitic stratovolcano that collapsed partly at ca. 2500 years ago. A post collapse lahar deposit (Shirayukigawa lahar deposit) is distributed in the northern foot of the volcanic edifice. The deposit consists of 16 units of debris flow, hyperconcentrated flow and streamflow deposits. The Shirayukigawa lahar deposit has a total thickness of 30 m and overlies the 2.5-ka Kisakata debris avalanche deposit. Shirayukigawa lahar deposit forms volcanic fan and volcanic apron. The volcanic fan is subdivided into four areas on the basis of slope angles and of geomorphological features: 1) steeply sloped area, 2) moderately sloped area, 3) gently sloped area and 4) horizontal area. From sedimentary facies and structures, each unit of the Shirayukigawa lahar deposit is classified into one of four lithotypes: clast-supported debris flow deposit (Cc), matrix-supported debris flow deposit (Cm1), hyperconcentrated flow deposit (Cm2) and streamflow deposit (Sl). Each type has the following lithological characteristics. The lithotypes are well correlated with the geomorphology of the volcanic fan. The steeply-sloped and the moderately-sloped areas are dominated by Cc, Cm1, and Cm2, and The horizontal area are dominated by Sl. Debris flow deposit (Cc) is massive, very poorly sorted, partly graded, and clast-supported with polymictic clasts dominated by subrounded to rounded volcanic clasts. Matrix is sandy to muddy. Preferred clast orientation are present. Debris flow deposit (Cm1) is massive, very poorly sorted, and matrix-supported with polymictic clasts dominated by subrounded to rounded volcanic clasts. Matrix is sandy to muddy. Some layers exhibit coarse-tail normal/inverse grading. Most clasts are oriented. Hyperconcentrated flow deposit (Cm2) is massive to diffusely laminated, very poorly sorted and matrix-supported with polymictic clasts dominated by subrounded to rounded volcanic rocks. Matrix is sandy. The

  6. A Mechanism for the Production of Calc-alkalic and Tholeiitic Magma Series in Azuma Volcano, Northeast Japan

    NASA Astrophysics Data System (ADS)

    Hirahara, Y.; Takahashi, T.; Chang, Q.; Miyazaki, T.; Kimura, J.; Tatsumi, Y.

    2009-12-01

    Two types of magma series, calc-alkalic (CA) and tholeiitic (TH), are recognized in the sub-alkalic volcanic rocks from Quaternary volcanoes on the volcanic front of the northeast (NE) Japan arc. Previous work proposed that the trend for the CA series could be reproduced by differentiation of hydrous basaltic magmas. However, petrographical and geochemical characteristics of CA rocks commonly indicate that the CA series is derived from mixing between mafic and felsic magmas (e.g. Zao volcano; Tatsumi et al., 2008). We propose a mechanism to generate the two magma series in rocks from Azuma volcano, located south of Zao volcano. The petrographical characteristics of TH series rocks from Azuma indicate that magma mixing does not, or only slightly, influences their genesis. Those of the CA series rocks, on the other hand, provide strong evidence for magma mixing (e.g., the presence of a disequilibrium phenocryst assemblage of Mg-rich olivine and quartz, the wide and bimodal compositions of plagioclase phenocrysts in terms of Ca/(Ca+Na), and the honeycomb textures and dusty zones commonly in these plagioclase phenocrysts). Major and trace element variation diagrams for the CA series show straight-line trends, which could be explained by mixing of mafic and felsic end-members. In the Azuma volcanic rocks, isotopic compositions (87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb) of basalts from the CA series have less radiogenic compositions (e.g., 87Sr/86Sr < 0.7039) than those of basalts from the TH series (e.g., 87Sr/86Sr > 0.7055). This indicates different sources for the CA and TH basalts. Intermediate rocks from the CA series have more enriched radiogenic compositions (e.g., 87Sr/86Sr = 0.7044 - 0.7048) than the CA basalts. The results indicate the felsic end-member of the CA series has a higher radiogenic composition than its mafic end-member. The unmixed TH basalts from Azuma have higher radiogenic compositions than those of the TH basalts from Zao

  7. A subsurface structure change associated with the eruptive activity at Sakurajima Volcano, Japan, inferred from an accurately controlled source

    NASA Astrophysics Data System (ADS)

    Maeda, Yuta; Yamaoka, Koshun; Miyamachi, Hiroki; Watanabe, Toshiki; Kunitomo, Takahiro; Ikuta, Ryoya; Yakiwara, Hiroshi; Iguchi, Masato

    2015-07-01

    Temporal variations of Green functions associated with the eruptive activity at Sakurajima Volcano, Japan, were estimated using an accurately controlled routinely operated signal system (ACROSS). We deconvolved 400 s waveforms of the ACROSS signal at nearby stations by a known source time function and stacked the results based on the time relative to individual eruptions and the eruption intervals; the quantities obtained by this procedure are Green functions corresponding to various stages of the eruptive activity. We found an energy decrease in the later phase of the Green functions in active eruptive periods. This energy decrease, localized in the 2-6 s window of the Green functions, is difficult to explain by contamination from volcanic earthquakes and tremors. The decrease could be more reasonably attributed to a subsurface structure change caused by the volcanic activity.

  8. Self-potential Anomalies Around the Earthquake Swarm Area in the Southeastern Flank of Ontake Volcano, Central Japan

    NASA Astrophysics Data System (ADS)

    Yoshimura, R.; Yamazaki, K.; Okada, Y.; Oshiman, N.

    2006-12-01

    Ontake Volcano is located in the southern end of the Norikura Volcanic Chain, central Japan, close to the junction of the Izu Bonin and Mariana and Southwestern Japan volcanic arcs. It is almost conical and made of andesite. Earthquake swarm activity has been continuously observed around the southeastern flank of Mt. Ontake since 1976. A phreatic explosion occurred in 1979 at a fissure on the southwestern slope of the Kengamine, the main peak of Mt. Ontake. And a large earthquake with the depth about 2 km and a magnitude of 6.8 occurred in 1984 in the southeastern flank of the volcano. Recently, Kimata et al. (2004) revealed uplift ground deformation above the earthquake swarm area by using repeated leveling. Furthermore, Magnetotelluric soundings estimated a low resistivity region with the depth about 2km beneath the uplift area [Kasaya et al., 2002]. In order to investigate a relationship between tectonic movements and subsurface low resistivity zone, we carried out self-potential(SP) measurements from 2003 and 2006 around the focal region of the 1984 Earthquake and the summit area of Mt. Ontake. The equipment for measuring surface self-potentials consists of a pair of non-polarizing copper-copper sulfate/silver-silver chloride electrodes, an insulated connecting conductor cable, and a high input impedance digital multimeter. In this survey, profiles totaling to about 90km length (982 sites) were made, with an average measurement interval of 100m. Two distinctive SP features are found around the active earthquake cluster and inside of the aseismic area of southeastern flank of Mt. Ontake. In this presentation, we will report a detail of SP measurements and results.

  9. Lava flow hazards-An impending threat at Miyakejima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Cappello, Annalisa; Geshi, Nobuo; Neri, Marco; Del Negro, Ciro

    2015-12-01

    The majority of the historic eruptions recorded at Miyakejima volcano were fissure eruptions that occurred on the flanks of the volcano. During the last 1100 years, 17 fissure eruptions have been reported with a mean interval of about 76-78 years. In the last century, the mean interval between fissure eruptions decreased to 21-22 years, increasing significantly the threat of lava flow inundations to people and property. Here we quantify the lava flow hazards posed by effusive eruptions in Miyakejima by combining field data, numerical simulations and probability analysis. Our analysis is the first to assess both the spatiotemporal probability of vent opening, which highlights the areas most likely to host a new eruption, and the lava flow hazard, which shows the probabilities of lava-flow inundation in the next 50 years. Future eruptive vents are expected in the vicinity of the Hatchodaira caldera, radiating from the summit of the volcano toward the costs. Areas more likely to be threatened by lava flows are Ako and Kamitsuki villages, as well as Miike port and Miyakejima airport. Thus, our results can be useful for risk evaluation, investment decisions, and emergency response preparation.

  10. Li and Sr isotope systematics of spring water around Ontake volcano in Japan: origin of fluid causes crustal deformation

    NASA Astrophysics Data System (ADS)

    Nishio, Y.; Okamura, K.; Sano, Y.

    2008-12-01

    Since 1978, earthquake swarms have been observed continuously on the east flank of Ontake volcano in central Japan. Earthquakes bigger than M4 have been occurred one or two a year. In September 1984, the M6.8 Western Nagano Prefecture earthquake occurred, and the Otaki village was devastating by collapse of volcanic edifice. In this earthquake swarm region, uplift of 3-6mm has been detected in 2002-2004 (Kimata et al., 2004). Also, a low-resistivity region at a depth 2km beneath the uplift area has been inferred from specific electric conductivity measurements (Kasaya et al., 2002). The resistivity index is lower than 100 ohm/m, suggesting the presence of hydrothermal chamber rather than magma. Our research group has carried out continuous geochemical survey for gas in hot and mineral springs around Ontake volcano since 1981. The results show that an anomalous increase in δ13C of CO2 and 3He/4He ratios was observed at the Shirakawa spring that is near the region of uplift (Takahata et al., 2003). Based on these features, it has been inferred that the observed uplift is related to changes in a shallow seismogenic layer due to increased hydrothermal input from the earthquake swarp area (Kimata et al., 2004). However, it has been unknown that the origin of the hydrothermal fluid that causes crustal deformation. The non-traditional lithium (Li) isotopic tracer has a great potential to provide us new knowledge for fluid that causes crustal deformation. Accordingly, we have analyzed 7Li/6Li ratios together with 87Sr/86Sr ratios and chemical compositions of filtrated spring water around Ontake volcano. Analyzed hot and mineral spring water has been sampled biennially since 2000. The results show that the delta 7Li values of spring water from the earthquake swarm region that is located in east flank of Ontake volcano are significantly lower than those of island arc volcanic rocks (δ7Li = ca. +3 ~ +5 per mil). From this, it is inferred that the fluid that causes crustal

  11. Budget of shallow magma plumbing system at Asama Volcano, Japan, revealed by ground deformation and volcanic gas studies

    NASA Astrophysics Data System (ADS)

    Kazahaya, Ryunosuke; Aoki, Yosuke; Shinohara, Hiroshi

    2015-05-01

    Multiple cycles of the intensive volcanic gas discharge and ground deformation (inflation and deflation) were observed at Asama Volcano, Japan, from 2000 to 2011. Magma budget of the shallow magma plumbing system was estimated on the basis of the volcanic gas emission rates and ground deformation data. Recent inflations observed in 2004 and 2008 were modeled as a dike intrusion to 2-3 km west of Asama Volcano. Previous studies proposed that magma ascends from a midcrustal magma reservoir to the dike and reaches the surface via a sinuous conduit which connects the dike to the summit. The intensive volcanic sulfur dioxide discharge of up to 4600 t/d at the volcano was modeled by magma convective degassing through this magma pathway. The volcano deflates as shrinkage of the magma in a reservoir by volcanic gas discharge. We estimated the volume change of the dike modeled based on the GPS observations, the volume decrease of the magma by the volcanic gas discharge, and the amount of degassed magma produced to calculate the magma budget. The results show that the volume decrease of the magma by the volcanic gas discharge was larger than the volume change of the dike during the inflation periods. This indicates that a significant volume of magma at least more than 2 times larger than the volume change of the dike was supplied from the midcrustal magma reservoir to the dike. The volume decrease of the dike was comparable with the volume decrease of the magma by the volcanic gas discharge during the deflation periods. The long-term deflation trend of the dike and the volume of degassed magma (108-9 m3) suggest that the degassed magma produced is not stored in the dike and the magma is mainly supplied from the midcrustal magma reservoir. In both periods, the volume of degassed magma produced was 1 order of magnitude larger than the volume change of the dike. This indicates that the actual volume of the magma supplied from the midcrustal magma reservoir is up to 1 order of

  12. Low to negligible BrO/SO2 ratios at two subduction-zone volcanoes

    NASA Astrophysics Data System (ADS)

    Bobrowski, Nicole; Hörmann, Christoph; Mori, Toshiya; Platt, Ulrich

    2014-05-01

    In July 2013 a measurement campaign took place on Kyushu, Japan, investigating the BrO/SO2 ratio in the plume of Sakurajima and Aso. Multi-Axis-Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were carried out at four sides on Sakurajima Island, with a maximum distance of about 5 km downwind, and assuming a wind speed of 5 m/s (corresponding to a plume age of about 15 minutes). At Aso measurements took place on the western slope of the active crater and at the crater rim. The MAX-DOAS data of both sites were evaluated for BrO and SO2 slant column densities (SCDs). In the following, BrO/SO2 ratios were calculated to overcome dilution effects and to investigate the BrO formation processes in the ash-laden plume of Sakurajima and the volcanic plume of Aso which is characterized by emissions from a fumarolic area and a mud pool. The BrO/SO2 ratios of the measurement have been below the detection limit for Aso as well as during most of the measurement days at Sakurajima with the only exception on 15th July 2013, when a BrO/SO2 ratio of ~ 1 x 10-5 could be determined. After very high BrO/SO2 ratios at Sakurajima that were reported by C. Lee et al. (2005) our results seem to be unexpected but nevertheless match the general geological settings at both volcanoes. In a recent paper, Shinohara (2013) summarized and compared chlorine emissions from the Japanese volcanic arc with global chlorine emissions from arc volcanoes and pointed out that the volcanic gas emissions in Japan are quite Cl-poor compared to those at other subduction zones. In the recent past it has been found that low chlorine emissions can occur together with nevertheless high bromine emissions (Nyiragongo, Bobrowski et al., 2013). However, looking up Br/Cl ratios (of condensate measurements at fumaroles) of the Japanese arc volcanism summarized in Gerlach, 2004 a comparatively low Br/Cl ratio is added with 6-7 x 10-4 (global arc mean 2 x 10-3) to the already poor chlorine emissions. We

  13. Development of the very long-range cosmic-ray muon radiographic imaging technique to explore the internal structure of an erupting volcano, Shinmoe-dake, Japan

    NASA Astrophysics Data System (ADS)

    Kusagaya, T.; Tanaka, H. K. M.

    2015-11-01

    Muography offers us a tool to observe hazardous erupting volcanoes remotely. However, practical muographic observations of volcanoes from a distance are difficult; therefore, various observations have been performed in the vicinity (< 1.5 km) of volcano peaks to suppress background noise and enhance images. In this study, we created a muographic image directly beneath the caldera floor of the erupting Shinmoe-dake volcano in Japan by locating our muography telescope 5 km from the peak. The Shinmoe-dake volcano began to erupt on 19 January 2011 and, in less than 1 month, the ejected lava almost completely filled the caldera and completely changed the topography of the caldera floor. The resultant image shows a low-density region underneath the western part of the newly created caldera floor, which indicates the existence of a void there. After the volcano became less active in February 2011, infrequent eruptions might have left a void beneath the caldera floor, which may trigger a collapse in the future. We anticipate that our novel muography will be a practical tool for monitoring and predicting eruption sequences in the near future.

  14. Development of the very long range muographic imaging technique to explore the internal structure of an erupting volcano, Shinmoe-dake, Japan

    NASA Astrophysics Data System (ADS)

    Kusagaya, T.; Tanaka, H. K. M.

    2015-07-01

    Muography offers us a tool to observe hazardous erupting volcanoes remotely. However, practical muographic observations of volcanoes from a distance are difficult; therefore, various observations have been performed in the vicinity (< 1.5 km) of volcano peaks to suppress background noise and enhance images. In this study, we created a muographic image directly beneath the caldera floor of the erupting Shinmoe-dake volcano in Japan by locating our muography telescope 5 km from the peak. Shinmoe-dake volcano began to erupt on 19 January 2011, and in less than one month, the ejected lava almost completely filled the caldera and completely changed the topography of the caldera floor. The resultant image shows a low-density region underneath the western part of the newly created caldera floor, which indicates the existence of a void there. After the volcano became less active in February 2011, infrequent eruptions might have left a void beneath the caldera floor, which may trigger a collapse in the future. We anticipate that our novel muography will be a practical tool for monitoring and predicting eruption sequences in the near future.

  15. Time series analysis of discolored seawater reflectance observed by Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2) at Fukutoku-Okonaba submarine volcano, Japan

    NASA Astrophysics Data System (ADS)

    Urai, Minoru

    2014-01-01

    Monitoring submarine volcanoes is not an easy task compared to land volcanoes because they are covered by seawater and located in remote areas. Satellite remote sensing is a powerful tool for monitoring underwater volcanic activities such as discolored seawater, floating material and volcanic plumes. Discolored seawater is a good indicator of submarine volcanic activities. Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2) made extensive observations from 2006 to 2011 of the Fukutoku-Okanoba submarine volcano, which is located 1300 km south of Tokyo, and is one of the most active submarine volcanoes in Japan. The high discolored seawater brightness coincides with relatively high activity of Fukutoku-Okanoba. No discolored seawater was observed for 6 months before the 2010 Fukutoku-Okanoba submarine eruption, meaning that Fukutoku-Okanoba was quiescent before the eruption. Both high brightness and apparent color change of discolored seawater derived from AVNIR-2 mean emergence of large amount of hot spring water, implying that the submarine volcano is highly active. This study demonstrates that satellite remote sensing is an effective tool for monitoring activities of inaccessible submarine volcanoes.

  16. Preparatory process preceding the 2014 eruption of Mount Ontake volcano, Japan: insights from precise leveling measurements

    NASA Astrophysics Data System (ADS)

    Murase, Masayuki; Kimata, Fumiaki; Yamanaka, Yoshiko; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Matsushima, Takeshi; Mori, Hitoshi; Ohkura, Takahiro; Yoshikawa, Shin; Miyajima, Rikio; Inoue, Hiroyuki; Mishima, Taketoshi; Sonoda, Tadaomi; Uchida, Kazunari; Yamamoto, Keigo; Nakamichi, Harushisa

    2016-01-01

    Preparatory activity preceding the 2014 eruption of Mount Ontake volcano was estimated from vertical deformation detected using a precise leveling survey. Notable uplift (2006-2009) and subsidence (2009-2014) were detected on the eastern flank of the volcano. We estimated pressure source models based on the vertical deformation and used these to infer preparatory process preceding the 2014 eruption. Our results suggest that the subsidence experienced between 2009 and 2014 (including the period of the 2014 eruption) occurred as a result of a sill-like tensile crack with a depth of 2.5 km. This tensile crack might inflate prior to the eruption and deflate during the 2014 activity. A two-tensile-crack model was used to explain uplift from 2006 to 2009. The geometry of the shallow crack was assumed to be the same as the sill-like tensile crack. The deep crack was estimated to be 2 km in length, 4.5 km in width, and 3 km in depth. Distinct uplifts began on the volcano flanks in 2006 and were followed by seismic activities and a small phreatic eruption in 2007. From the partially surveyed leveling data in August 2013, uplift might continue until August 2013 without seismic activity in the summit area. Based on the uplift from 2006 to 2013, magma ascended rapidly beneath the summit area in December 2006, and deep and shallow tensile cracks were expanded between 2006 and 2013. The presence of expanded cracks between 2007 and 2013 has not been inferred by previous studies. A phreatic eruption occurred on 27 September 2014, and, following this activity, the shallow crack may have deflated.

  17. Effect of subduction components on production of basalts from Tateshina volcano, central Japan: geochemical calculation of dehydration of subducting oceanic crust and partial melting of overlying sediments, and subsequent fluid-mantle interaction

    NASA Astrophysics Data System (ADS)

    Katoh, Masayasu; Shuto, Kenji

    Effect of subduction components on production of basalts from Tateshina volcano, central Japan: geochemical calculation of dehydration of subducting oceanic crust and partial melting of overlying sediments, and subsequent fluid-mantle interaction

  18. The 1997 phreatic eruption of Akita-Yakeyama volcano, northeast Japan: Insight into the hydrothermal processes

    NASA Astrophysics Data System (ADS)

    Nogami, K.; Hirabayashi, J.; Ohba, T.; Yoshiike, Y.

    2000-04-01

    A small-scale steam explosion occurred on Karanuma crater on the summit of Akita-Yakeyama volcano on August 16, 1997 after a dormancy of 46 years. Chemical compositions of the fumarolic gases at the summit and hot spring waters around the volcano were monitored before the eruption.Obvious changes in the composition and outlet temperatures of the fumarolic gases were not detected, neither before nor after the 1997 eruption. Hydrogen and oxygen isotopic ratios of the gas condensates and hot-spring waters at the Yunuma crater indicated that a hydrothermal reservoir, where the fumarolic gases separated from the hot-spring waters at 150circC, existed in a shallow place beneath the crater.Smectite, kaolinite and pyrophyllite were identified in the clay fraction of the volcanic ejecta. Although pyrophyllite should have been formed at about 1~km beneath the summit, it was not directly derived from the deep zone during the 1997 eruption but had been ejected by previous eruptions. The Cl/S values of the water leachates of the ejecta were about 0.7, which indicated that the volcanic gas which caused the eruption was rich in HCl. However, the fumarolic gases and the water samples collected from the summit area contained little chloride. The source of the water-soluble chloride might be high-temperature magmatic gases that have been estimated as the source of Cl-SO4 type thermal water. Such magmatic gases might have caused the 1997 eruption.

  19. Monitoring of volcanic gas composition at Asama volcano, Japan, during 2004-2014

    NASA Astrophysics Data System (ADS)

    Shinohara, Hiroshi; Ohminato, Takao; Takeo, Minoru; Tsuji, Hiroshi; Kazahaya, Ryunosuke

    2015-09-01

    The composition of the volcanic gases discharged from the summit crater of Asama volcano has been monitored since 2004 by Multi-GAS and alkaline-filter techniques. The persistent degassing activity at Asama volcano is characterized by large variation of SO2 flux. The CO2/SO2 and H2O/SO2 ratios did not show clear variation irrespective of the SO2 flux variation and a few eruptions that occurred during active degassing periods. The estimated ratios have large uncertainty due to variable contribution of the different fumaroles in the summit crater to the volcanic plume and lack of a systematic variation can be due to the large uncertainty. The SO2/Cl ratio showed a systematic decrease after the eruption to the inactive period, suggesting that degassing pressure did not significantly increase after the eruption. Low-pressure degassing along with the continuous and intensive gas discharge suggests that the degassing is due to conduit magma convection. The apparently stable CO2/SO2 ratios imply a lack of significant volatile differentiation in the magma reservoir, such as CO2-rich bubble accumulation. The large variation of the SO2 flux along with stable gas composition implies that the large changes in magma convection rate are caused by changes in the radius of the convecting magma conduit.

  20. Temporal changes in thermal waters related to volcanic activity of Tokachidake Volcano, Japan: implications for forecasting future eruptions

    NASA Astrophysics Data System (ADS)

    Takahashi, Ryo; Shibata, Tomo; Murayama, Yasuji; Ogino, Tagiru; Okazaki, Noritoshi

    2015-01-01

    In order to detect changes in volcanic activity of Tokachidake Volcano, Japan, we have continuously monitored thermal waters discharging at the western to southwestern flank of the volcano since 1986. The steam-heated waters in the Nukkakushi crater discharged with boiling temperature until 2002. Thermal waters at the Tokachidake spa area have similar compositions to fumarolic gas emitted from the summit craters, indicating that the waters formed by absorption of volcanic gas into shallow aquifers. Thermal waters at the Fukiage spa area were derived from the same aquifer as the Tokachidake spa area until early 1986. However, after that time, NaCl-type thermal water entered the Fukiage spa area during the increase in volcanic activity associated with the 1988-1989 eruption, thus leading to a clear increase in Cl concentrations and temperature. After the eruption, the supply of the NaCl-type thermal water was halted, and the Cl concentrations of the thermal waters decreased. In contrast, SO4 concentrations gradually increased in the Fukiage spa area after 1989, and the temperature has been maintained. These observations indicate that SO4-rich thermal water with a relatively high temperature entered the system instead of the NaCl-type thermal water. As was the case for the 1988-1989 eruption, the Cl concentrations at the Fukiage spa area increased in 2012 during an increase in volcanic activity, implying that the supply of the NaCl-type thermal water had resumed. However, the chemical changes in the thermal waters since 2012 are small compared with those before the 1988-1989 eruption, with oxygen and hydrogen isotopic compositions remaining nearly the same as those of meteoric waters.

  1. Magma generation process beneath volcanic front of Kyushu arc, southwest Japan

    NASA Astrophysics Data System (ADS)

    Tamura, T.; Hasenaka, T.; Wallace, P. J.; Yasuda, A.; Mori, Y.

    2015-12-01

    We presents data for major and volatile (H2O, CO2, S, Cl) elements in olivine-hosted melt inclusions from Quaternary volcanoes (Aso, Kuju, Kirishima and Kaimon) along volcanic front of Kyushu arc, southwest Japan. Melt inclusion data are corrected for post-entrapment modifications including diffusive Fe-loss, H2O loss and post-entrapment crystallization. The primitive magma compositions calculated from corrected melt inclusion data are used to estimate the degree of partial melting and compositions of slab-derived fluids beneath Kyushu volcanic front. The result show that magmatism of four volcanoes in Kyushu arc is divided into two groups (Group A and B). Group A indicates high K2O contents in primitive magmas and in fluids at Aso and Kuju volcanoes, northern Kyushu arc. Group B indicates low K2O contents in primitive magmas and in fluids at Kirishima and Kaimon volcanoes, southern Kyushu arc. K2O contents of Group A and B are impossible of explaining by degree of partial melting and the origin of hydrous mantle. High K2O content in fluids is attributed to dehydration of phengite-bearing slab at deep depth (about 140 km) in Group A compared with shallow depth (about 100 km) in Group B. Phengite is dehydrated from submerging plate beneath 110 km depth. This study suggests that compositions of primitive magmas beneath Kyushu arc are reflected by the depth of slab and the kind of dehydrating hydrous minerals.

  2. Stress perturbation given on the Mount Fuji Volcano Magma System caused by the Tohoku Megathrust Earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Fujita, E.; Kozono, T.; Ozawa, T.; Ueda, H.; Kohno, Y.; Yoshioka, S.; Toda, N.; Kikuchi, A.; Ida, Y.

    2012-12-01

    Earthquake often triggers volcanic eruptions nearby, and its mechanism is widely discussed. The megathrust earthquake on March 11, 2011, in Tohoku, Japan, caused enormous crustal deformation over the mainland of Japan, and 20 volcanoes showed abnormal activities. In this presentation, we evaluate the perturbation given on Mount Fuji volcanic system. We applied the Finite-Element Method (FEM) to calculate both static and quasi-static stress changes. The Japanese main-land and the Mount Fuji region are modeled based on seismic tomography, as well as the effects of the topography. Our results changes indicate that the static stress change due to Tohoku earthquake is in the order of 0.01MPa. In addition, an induced Mw5.9 East-Shizuoka earthquake occurred four days after the major earthquake beneath the south flank of Mount Fuji. This seismic fault is estimated to be located above the magma reservoir in the mid-crust, based on the inversion of ground deformation data, and FEM result suggests the stress changes of 0.1-1MPa. We also consider the quasi-static model to evaluate the mechanism of time lag between earthquakes and volcanic eruption. We applied the visco-elastic (Maxwell) model to crustal structure. We must obtain strain velocity in each time step, which controls the response after. Our results shows that the differential stress around the main shock region will reduce to 78 % of the static stress change in 100 years, but will increase to 7% of the static stress change beneath the magma reservoir of Mount Fuji volcano. Our interest is in whether these disturbances are sufficient to excite the magma and trigger and eruption. Here we consider two kinds of processes leading to an eruption. The first one is the promotion of the promotion of bubbling due to depressurization, and the other is the stress changes in the surrounding rocks. We performed numerical simulations of depressurization bubbling by VERA code (Fujita et al., 2007, IUGG). We assume initial bubble

  3. Sequence of the 1895 eruption of the Zao volcano, Tohoku Japan

    NASA Astrophysics Data System (ADS)

    Miura, Kotaro; Ban, Masao; Ohba, Tsukasa; Fujinawa, Akihiko

    2012-12-01

    The most recent major eruption event of the Zao volcano comprised a series of phreatic eruption episodes on 15 and 19 February, 22 August, and 27-28 September 1895, with several precursory vulcanian eruptions during February-July 1894. All were generated at the Okama crater lake located inside the Umanose caldera. The eruption products consist mainly of hydrothermally altered ash with altered blocks, except for ash from 1984. The eruption deposits of 1895 are divided lithologically into six layers (1-6). Comparison of the document with the lithofacies of deposits shows that layers 1, 2, 3-4, and 5-6 were correlated respectively with eruption episodes of 15 February (episode 1), 19 February (episode 2), 22 August (episode3), and 27-28 September (episode 4). During these four episodes, ca. 0.5%, 0.5%, 1.5%, and 98% of the total mass of the products had been discharged. Based on lithologic, stratigraphic, granulometric, and component analyses and on distributional features for these layers, the following depositional mechanisms were inferred. Layers 1, 3, and 4 were formed mainly from their related small pyroclastic density currents, whereas layer 2 resulted mainly from a small pyroclastic fall. In contrast, layers 5 and 6 are larger-scale near-vent pyroclastic fall deposits from ash clouds and eruption clouds, which might have included some juvenile fragments. The three early episodes in 1985 led to the climactic episode of 27-28 September. Furthermore, the andesitic magma chamber at < 3 kb depth, which caused the 1894 vulcanian eruptions, became a hydrothermal alteration source for the 1895 erupted materials. The chamber was re-activated before 1895 eruption by injection of basaltic magmas from greater depth. The injection reached maximum at the climactic event. The inferred course of that series of eruption episodes provides useful information to predict future volcanic phreatic-type eruptions at this volcano.

  4. CO2 emission from lake-filled Katanuma crater, Narugo volcano, Japan

    NASA Astrophysics Data System (ADS)

    Padron, E.; Hernandez Perez, P. A.; Mori, T.; Perez, N.

    2010-12-01

    Narugo volcano is composed by four dacitic Holocene age lava domes surrounding the 400 m wide lake-filled Katanuma crater. A large caldera, 5.5 x 7 km NW of the city of Sendai was formed by paroxysmal eruptions 45 ka ago and after this activity, lava flows and lava domes were formed in the inner part of the caldera. The only known eruption at Narugo in historical time occurred in 837 AD. Katanuma is known as one of the most acidic lakes in the world and boiling springs, water vapour and volcanic gases are discharged from the lake botton. As a result of this degassing, a relatively intense volcanic gas emission is observed along the lake surface in the form of gas bubbles. To compute the total CO2 degassing rate through Katanuma water lake surface, a CO2 emission survey was carried out on August 2010. CO2 efflux measurements were performed on the water surface by means of a portable NDIR sensor at 86 sampling sites, following a modified floating device of the accumulation chamber method.CO2 efflux values ranged between 16 and 14300 g m-2 d-1. CO2 efflux map was constructed using sequential Gaussian simulation. An important CO2 degassing structure was observed at the water surface, located on its west half part, with a N-S trending. An averaged map of 200 equiprobable simulations allowed us to compute 35.2 ± 4.1 t/d of CO2 released to the atmosphere through the water surface on a area of 0.14 km2. These results suggest clearly that monitoring CO2 emission rate from lake-filled Katanuma crater will contribute to improve the Narugo volcano surveillance program as well as our knowledge on the global CO2 emission from volcanic lakes, which is actually estimated about 136 Mt year-1 (Pérez et al., 2010). Reference: Pérez et al., 2010. CVL 7 Workshop Costa Rica, March 2010.

  5. Magma discharge variations during the 2011 eruptions of Shinmoe-dake volcano, Japan, revealed by geodetic and satellite observations

    NASA Astrophysics Data System (ADS)

    Kozono, Tomofumi; Ueda, Hideki; Ozawa, Taku; Koyaguchi, Takehiro; Fujita, Eisuke; Tomiya, Akihiko; Suzuki, Yujiro J.

    2013-03-01

    We present precise geodetic and satellite observation-based estimations of the erupted volume and discharge rate of magma during the 2011 eruptions of Kirishima-Shinmoe-dake volcano, Japan. During these events, the type and intensity of eruption drastically changed within a week, with three major sub-Plinian eruptions on January 26 and 27, and a continuous lava extrusion from January 29 to 31. In response to each eruptive event, borehole-type tiltmeters detected deflation of a magma chamber caused by migration of magma to the surface. These measurements enabled us to estimate the geodetic volume change in the magma chamber caused by each eruptive event. Erupted volumes and discharge rates were constrained during lava extrusion using synthetic aperture radar satellite imaging of lava accumulation inside the summit crater. Combining the geodetic volume change and the volume of lava extrusion enabled the determination of the erupted volume and discharge rate during each sub-Plinian event. These precise estimates provide important information about magma storage conditions in magma chambers and eruption column dynamics, and indicate that the Shinmoe-dake eruptions occurred in a critical state between explosive and effusive eruption.

  6. Progressive enrichment of arc magmas caused by the subduction of seamounts under Nishinoshima volcano, Izu-Bonin Arc, Japan

    NASA Astrophysics Data System (ADS)

    Sano, Takashi; Shirao, Motomaro; Tani, Kenichiro; Tsutsumi, Yukiyasu; Kiyokawa, Shoichi; Fujii, Toshitsugu

    2016-06-01

    The chemical composition of intraplate seamounts is distinct from normal seafloor material, meaning that the subduction of seamounts at a convergent margin can cause a change in the chemistry of the mantle wedge and associated arc magmas. Nishinoshima, a volcanic island in the Izu-Bonin Arc of Japan, has been erupting continuously over the past 2 years, providing an ideal opportunity to examine the effect of seamount subduction on the chemistry of arc magmas. Our research is based on the whole-rock geochemistry and the chemistry of minerals within lavas and air-fall scoria from Nishinoshima that were erupted before 1702, in 1973-1974, and in 2014. The mineral phases within the analyzed samples crystallized under hydrous conditions (H2O = 3-4 wt.%) at temperatures of 970 °C-990 °C in a shallow (3-6 km depth) magma chamber. Trace element data indicate that the recently erupted Nishinoshima volcanics are much less depleted in the high field strength elements (Nb, Ta, Zr, Hf) than other volcanics within the Izu-Bonin Arc. In addition, the level of enrichment in the Nishinoshima magmas has increased in recent years, probably due to the addition of material from HIMU-enriched (i.e., high Nb/Zr and Ta/Hf) seamounts on the Pacific Plate, which is being subducted westwards beneath the Philippine Sea Plate. This suggests that the chemistry of scoria from Nishinoshima volcano records the progressive addition of components derived from subducted seamounts.

  7. Japan.

    ERIC Educational Resources Information Center

    Geiger, Rita; And Others

    The document offers practical and motivating techniques for studying Japan. Dedicated to promoting global awareness, separate sections discuss Japan's geography, history, culture, education, government, economics, energy, transportation, and communication. Each section presents a topical overview; suggested classroom activities; and easily…

  8. Stable Isotope Anomalies and Low Chloride Concentrations in Pore Water of CH4-Rich Sediments at the Tanegashima Mud Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Nakayama, N.; Tsunogai, U.; Ashi, J.; Gamo, T.

    2004-12-01

    Pore water from sediments collected at a Tanegashima mud volcano was analyzed for δ 13C (PDB) of dissolved CH4 together with other chemical components, Cl- and SO42-, and the δ 18O and δ D (SMOW). The Tanegashima mud volcanoes are located at the water depths from 1400 m to 1800 m, off Tanegashima island between Ryukyu trench and Ryukyu arc of Japan. It is situated at the end of south-western convergent plate boundary on Nankai-trough, which forms a part of Philippine Sea plate subducting under Eurasian plate. This cruise was conducted as a part of the JNOC (Japan National Oil Corporation) geochemical survey by R/V Hakurei-maru II. The concentrations of CH4 were generally higher than 100 micro-mol/kg. Its highest concentration (715 micro-mol/kg) was found in the crest core of a mud volcano. The δ 13C values ranged from -32 to -50 ‰ . C2H6 was detected only in the pore waters collected from the vicinity of the crest of the mud volcano. The highest δ 13C (around -22 ‰ ) and low C1/C2 concentration ratios (less than 100) were measured at the crest site, supporting the thermogenical production of methane. Other geochemical anomalies were also observed in the crest pore water. The concentrations of Cl- in the pore water at this site were extremely depleted to a minimum of 350 mmol/kg. The Cl- anomaly has not been previously reported for pore water from mud volcanoes around Japan. An endmember of isotopic composition of the fluid is estimated to be +12 ‰ for δ 18O and -40 ‰ for δ D. From these results we conclude that the most likely process to reduce pore water salinity is primarily the mixing of clay mineral dehydration water with seawater. The thermogenic methane found in the crest pore waters of the Tanegashima mud volcano may be brought from the depths of sediments due to the migration of fluid evolved by mineral the dehydration process.

  9. Acid alteration in the fumarolic environment of Usu volcano, Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Africano, F.; Bernard, A.

    2000-04-01

    The last eruptive activity of Usu volcano in 1977-78 involved the development of high temperature (550-710°C) fumaroles. The gases emitted were H 2O-rich (95-99 mol%) with Cl/S=0.05-0.9, F/Cl=0.3-0.2 and with RH=-2.5 close to the rock buffer (FeO/FeO 1.5). Cooling and oxidation of the high temperature gases resulted in the formation of acidic condensates (pH=1.6) that interacted with the wall rock. Complete leaching of the cations (Ca, Na, Mg, Al and Fe) from the primary minerals and matrix glass occurred leaving in place only silica. These mobilized cations precipitated as secondary minerals from acidic fluids that circulated in microcracks. SEM study shows mineral associations reflecting increasing fluid oxidation: (a) Al fluorides such as ralstonite (NaMgAlF 6·H 2O), pyrite, and anhydrite/gypsum; (b) an Al hydroxide, hematite, gypsum and amorphous silica or cristobalite; (c) Al sulfates such as hydronium alunite [(H 3O)Al 3(SO 4) 2(OH) 6], alunite [KAl 3(SO 4) 2(OH) 6], amorphous silica, cristobalite, hematite and anhydrite/gypsum; (d) Al sulfates, Al fluorides, amorphous silica, cristobalite, pyrite and anhydrite/gypsum. A Ti oxide, a Fe-Mg sulfate and barite are present in minor amounts. Clay minerals are absent from the observed assemblages. Primary phenocrysts and matrix glass undergo a complete transformation to silica enriched in fluorine (1-7 wt%). This fluorine enrichment in the silicified parts of silicates and in silica incrustations suggests that F may play a role in silica mobilization. Modeling of the cooling of the high-temperature gases was performed with the program GASWORKS. The calculations suggest that 66% of the total sulfur from the gases may be lost by deposition as native sulfur at temperatures below 160°C. Thermochemical modeling of condensate-rock interaction using CHILLER indicates that the cooling of gases was the source of the altering solutions. Oxidation, by atmospheric O 2, of the sulfur-reduced species in the volcanic gas

  10. Magma Feeding System of the Past ca. 30-ky Activities of the Zao Volcano, NE Japan

    NASA Astrophysics Data System (ADS)

    Ban, M.; Kotaro, M.; Takebe, Y.; Sato, H.; Sagawa, H.

    2006-12-01

    In the youngest stage (30 ka to present) of the Zao volcano, three active periods (ca. 31 to 29 ka, 7.5 to 4.1 ka, and 2.0 to present) can be observed. Piles of pyroclastic rocks by numerous small to medium sized eruptions are main products of the activities. In this study we examined the magma feeding system in the three periods, based on the petrologic features of the products. Rocks erupted in the three periods are olivine± pyroxene basaltic andesite to andesite, and these were formed by mixing of two end-member magmas, judged from the petrographic and mineralogic features. The estimated felsic end-members are similar among the periods, andesite (ca.60% in silica content) with orthopyroxene (Mg#=ca.64), clinopyroxene (Mg#=ca.68), plagioclase (An=ca.65) phenocrysts. The estimated mafic end-members are basalt with olivine (Fo=ca.80) and plagioclase (An=ca.90) phenocrysts in all periods, however, the bulk MgO, Cr and Ni contents of the erupted rocks are higher in the second period than in the other two periods. During the second and third periods, silica contents of the rocks decreased temporally from 58 to 55-56 % and recovered up to 58 %, and these variations can be explained by the different percentages of the basaltic magma involved in the mixing. Those features are suggesting that the mafic end-member magmas are distinct among periods, and may have been stored in the deeper part of the crust for ca.3.5 to 2.0 ky. Looking at the chemical compositions of rocks in the past ca.0.8-ky eruptions closely, gradual decrease in Zr (and increase in Cr) contents toward upper part can be seen at least twice, which may correspond to the progressive injection of the basaltic magma to the shallower andesitic magma chamber, and it is estimated that the duration of each injection is less than 0.2 ky.

  11. Long-term geochemical surveillance of fumaroles at Showa-Shinzan dome, Usu volcano, Japan

    USGS Publications Warehouse

    Symonds, R.B.; Mizutani, Y.; Briggs, P.H.

    1996-01-01

    This study investigates 31 years of fumarole gas and condensate (trace elements) data from Showa-Shinzan, a dacitic dome-cryptodome complex that formed during the 1943-1945 eruption of Usu volcano. Forty-two gas samples were collected from the highest-temperature fumarole, named A-1, from 1954 (800??C) to 1985 (336??C), and from lower-temperature vents. Condensates were collected contemporaneously with the gas samples, and we reanalyzed ten of these samples, mostly from the A-1 vent, for 32 cations and three anions. Modeling using the thermochemical equilibrium program, SOLVGAS, shows that the gas samples are mild disequilibrium mixtures because they: (a) contain unequilibrated sedimentary CH4 and NH3; (b) have unequilibrated meteoric water; or (c) lost CO, either by air oxidation or by absorption by the sodium hydroxide sampling solution. SOLVGAS also enabled us to restore the samples by removing these disequilibrium effects, and to estimate their equilibrium oxygen fugacities and amounts of S2 and CH4. The restored compositions contain > 98% H2O with minor to trace amounts of CO2, H2, HCl, SO2, HF, H2S, CO, S2 and CH4. We used the restored gas and condensate data to test the hypotheses that these time-series compositional data from the dome's fumaroles provide: (1) sufficient major-gas data to analyze long-term degassing trends of the dome's magma-hydrothermal system without the influence of sampling or contamination effects; (2) independent oxygen fugacity-versus-temperature estimates of the Showa-Shinzan dacite; (3) the order of release of trace elements, especially metals, from magma; and (4) useful information for assessing volcanic hazards. The 1954-1985 restored A-1 gas compositions confirm the first hypothesis because they are sufficient to reveal three long-term degassing trends: (1) they became increasingly H2O-rich with time due to the progressive influx of meteoric water into the dome; (2) their C/S and S/Cl ratios decreased dramatically while their Cl

  12. Frictional control on eruptive style at Mt. Unzen (Japan) and Santiaguito volcano (Guatemala)

    NASA Astrophysics Data System (ADS)

    Hornby, A. J.; Kendrick, J. E.; Hirose, T.; De Angelis, S.; Henton De Angelis, S.; Lavallee, Y.; Umakoshi, K.

    2013-12-01

    velocities led to increased melt productivity with a diminishing control on shear resistance at the slip zone. These relationships suggest a non-Newtonian rheology for frictional melt, which induces slip dynamics that do not abide to Byerlee's rule. We note that while the total slip required to undergo frictional melting diminishes with axial stress and slip velocity, Santiaguito dome samples required greater distances to achieve melting than Unzen samples (at the same conditions). Dome material from Santiaguito and Unzen show a remarkably similar mechanical response upon frictional melting. At shallow depths frictional melting may exert a viscous brake on slip, encouraging stick-slip behaviour at dome volcanoes. This study concludes that frictional melting changes the mechanical properties of rocks at a fault surface, and thus the rheology driving dome extrusion may not be derived directly from the relict dome material itself.

  13. Estimation of total discharged mass from the phreatic eruption of Ontake Volcano, central Japan, on September 27, 2014

    NASA Astrophysics Data System (ADS)

    Takarada, Shinji; Oikawa, Teruki; Furukawa, Ryuta; Hoshizumi, Hideo; Itoh, Jun'ichi; Geshi, Nobuo; Miyagi, Isoji

    2016-08-01

    The total mass discharged by the phreatic eruption of Ontake Volcano, central Japan, on September 27, 2014, was estimated using several methods. The estimated discharged mass was 1.2 × 106 t (segment integration method), 8.9 × 105 t (Pyle's exponential method), and varied from 8.6 × 103 to 2.5 × 106 t (Hayakawa's single isopach method). The segment integration and Pyle's exponential methods gave similar values. The single isopach method, however, gave a wide range of results depending on which contour was used. Therefore, the total discharged mass of the 2014 eruption is estimated at between 8.9 × 105 and 1.2 × 106 t. More than 90 % of the total mass accumulated within the proximal area. This shows how important it is to include a proximal area field survey for the total mass estimation of phreatic eruptions. A detailed isopleth mass distribution map was prepared covering as far as 85 km from the source. The main ash-fall dispersal was ENE in the proximal and medial areas and E in the distal area. The secondary distribution lobes also extended to the S and NW proximally, reflecting the effects of elutriation ash and surge deposits from pyroclastic density currents during the phreatic eruption. The total discharged mass of the 1979 phreatic eruption was also calculated for comparison. The resulting volume of 1.9 × 106 t (using the segment integration method) indicates that it was about 1.6-2.1 times larger than the 2014 eruption. The estimated average discharged mass flux rate of the 2014 eruption was 1.7 × 108 kg/h and for the 1979 eruption was 1.0 × 108 kg/h. One of the possible reasons for the higher flux rate of the 2014 eruption is the occurrence of pyroclastic density currents at the summit area.

  14. Japan.

    PubMed

    1989-02-01

    Japan consists of 3900 islands and lies off the east coast of Asia. Even though Japan is one of the most densely populated nations in the world, its growth rate has stabilized at .5%. 94% of all children go to senior high school and almost 90% finish. Responsibility for the sick, aged, and infirmed is changing from the family and private sector to government. Japan was founded in 600 BC and its 1st capital was in Nara (710-1867). The Portuguese, the 1st Westerners to make contact with Japan in 1542, opened trade which lasted until the mid 17th century. US Navy Commodore Matthew Perry forced Japan to reopen in 1854. Following wars with China and Russia in the late 1800s and early 1900s respectively, Japan took part in World Wars I and II. In between these wars Japan invaded Manchuria and China. The US dropped an atomic bomb on Hiroshima and Nagasaki and the Japanese surrendered in September, 1945 ending World War II (WWII). Following, WWII, the Allied Powers guided Japan's establishment as a nonthreatening nation and a democratic parliamentary government (a constitutional monarchy) with a limited defense force. Japan remains one of the most politically stable of all postwar democracies. The Liberal Democratic Party's Noboru Takeshita became prime minister in 1987. Japan has limited natural resources and only 19% of the land is arable. Japanese ingenuity and skill combine to produce one of the highest per hectare crop yields in the world. Japan is a major economic power, and its and the US economies are becoming more interdependent. Its exports, making up only 13% of the gross national product, mainly go to Canada and the US. Many in the US are concerned, however, with the trade deficit with Japan and are seeking ways to make trade more equitable. Japan wishes to maintain good relations with its Asian neighbors and other nations. The US and Japan enjoy a strong, productive relationship. PMID:12178004

  15. Chronology and products of the 2000 eruption of Miyakejima Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Nakada, S.; Nagai, M.; Kaneko, T.; Nozawa, A.; Suzuki-Kamata, K.

    2005-03-01

    Lateral migration of magma away from Miyakejima volcanic island, Japan, generated summit subsidence, associated with summit explosions in the summer of 2000. An earthquake swarm beneath Miyakejima began on the evening of 26 June 2000, followed by a submarine eruption the next morning. Strong seismic activity continued under the sea from beneath the coast of Miyakejima to a few tens of kilometers northwest of the island. Summit eruptive event began with subsidence of the summit on 8 July and both explosions and subsidence continued intermittently through July and August. The most intense eruptive event occurred on 18 August and was vulcanian to subplinian in type. Ash lofted into the stratosphere fell over the entire island, and abundant volcanic bombs were erupted at this time. Another large explosion took place on 29 August. This generated a low-temperature pyroclastic surge, which covered a residential area on the northern coast of the island. The total volume of tephra erupted was 9.3×106 m3 (DRE), much smaller than the volume of the resulting caldera (6×108 m3). Migration of magma away from Miyakejima was associated with crustal extension northwest of Miyakejima and coincident shrinkage of Miyakejima Island itself during July August 2000. This magma migration probably caused stoping of roof rock into the magma reservoir, generating subsurface cavities filled with hydrothermal fluid and/or magmatic foam and formation of a caldera (Oyama Caldera) at the summit. Interaction of hydrothermal fluid with ascending magma drove a series of phreatic to phreatomagmatic eruptions. It is likely that new magma was supplied to the reservoir from the bottom during waning stage of magma’s migration, resulting in explosive discharge on 18 August. The 18 August event and phreatic explosions on 29 August produced a conduit system that allowed abundant SO2 emission (as high as 460 kg s-1) after the major eruptive events were over. At the time of writing, inhabitants of the

  16. Mud plumbing system of an isolated phreatic eruption at Akita Yakeyama volcano, northern Honshu, Japan

    NASA Astrophysics Data System (ADS)

    Ohba, T.; Taniguchi, H.; Miyamoto, T.; Hayashi, S.; Hasenaka, T.

    2007-03-01

    A small phreatic eruption occurred on 16 August 1997 at the flank of a dacite lava dome of Akita Yakeyama, northern Honshu, Japan. Air-falls and viscous mudflows were discharged from two craters. Mudflow effusion preceded discrete explosions, followed by a fine ash discharge. The air-fall deposit consists of an upper fine ash deposit and a lower ballistic-dominated, poorly sorted tephra in which ranges in grain size from fine ash to blocks of ca. 50 cm. Both air fall and mudflow deposits were composed of fine mud and coarse lithic fragments, which contained abundant liquid water. Lithic fragments comprise fresh dacite of the host lava dome and hydrothermally altered stratocone andesite. Intensely altered andesite fragments contain quartz, cristobalite, andalusite, pyrophyllite, 7 Å-kaolin, and anhydrite. Some mineral assemblages indicate hydrothermal temperatures greater than 300 °C. Rare sandstone fragments are likely to be lacustrine from ca. 1000 m depth. The surface morphology of the mudflow deposits indicates that the mud contained ca. 30 vol.% water. The cube-root similarity rules on crater size and the cloud shape of buried explosions provided energy of 3-5 × 10 9 J at depths of 6-10 m, based on the observed crater size (20 m) and fountain-like cloud shape. The depth estimate is consistent with the abundance of coarse dacite fragments derived from shallow lava in the explosion deposit. Thermodynamic energy release of ca. 1 × 10 11 J was calculated based on the following estimated parameters: product volume of 1 × 10 3 m 3, hydrothermal temperatures of 300-350 °C, and pressures of 11-24 MPa corresponding to the estimated source depth. The thermodynamic estimation represents the total energy released during the eruption, whereas the similarity rule yields an energy value as created by discrete explosions. Mud ascended from a hot aquifer at 1000 m depth, first effused as a mudflow, and was then expelled explosively from another crater. Explosivity depends

  17. Electromagnetic and geochemical methods applied to investigations of hydrothermal/volcanic unrests: Examples of Taal (Philippines) and Miyake-jima (Japan) volcanoes

    NASA Astrophysics Data System (ADS)

    Zlotnicki, Jacques; Sasai, Y.; Toutain, J. P.; Villacorte, E.; Harada, M.; Yvetot, P.; Fauquet, F.; Bernard, A.; Nagao, T.; Phivolcs Team

    Magnetic, -electric and -electromagnetic phenomena (EM) are almost always observed on volcanoes before and during volcanic eruptions, if EM methods are well-designed and applied on the field. But unfortunately these methods are, most often, still used independently. They also do not benefit of dense inter-correlated networks which should allow more accurate results and fine modelling of the volcanic activity. On volcanoes which display hydrothermal/magmatic unrests, EM methods can be combined with geochemical (GC) methods. The integration of these methods allows us to image in detail hydrothermal systems, to find out possible scenarios of volcanic unrest, and to monitor the on-going activity with some knowledge on the sources of heat, gas and fluid transfers. The objectives of this paper is (1) to outline the appearance and the characteristics of EM signals before an eruptive event when multi-EM methods are applied on the field, (2) to sketch out the complementary between EM and GC methods when these methods are jointly applied on volcanic/hydrothermal systems. Two case studies are given in the paper. On Miyake-jima volcano in Japan integrated EM methods started in 1995. Although the seismicity only appeared 13 days before the July 8, 2000 collapse of the summit, changes in the magnetic field, electrical resistivity and electric potential have progressively appeared after 1996. Based on geophysical observations and on continuous magnetotelluric soundings, a synthesis of the EM observations allows proposing a coherent model of the volcano unrest. The second case study is Taal volcano in Philippines on which sporadic, but sometimes intense, seismic crises are observed since 1992. A strong and large scale hydrothermal system stands on the volcano and is periodically re-activated. Commonly applied since 2005, combined EM and GC methods give an accurate description of the hydrothermal activity and heat discharge. EM methods, as magnetic and self-potential, map the

  18. Long-term geochemical surveillance of fumaroles at Showa-Shinzan dome, Usu volcano, Japan

    NASA Astrophysics Data System (ADS)

    Symonds, Robert B.; Mizutani, Yoshihiko; Briggs, Paul H.

    1996-10-01

    This study investigates 31 years of fumarole gas and condensate (trace elements) data from Showa-Shinzan, a dacitic dome-cryptodome complex that formed during the 1943-1945 eruption of Usu volcano. Forty-two gas samples were collected from the highest-temperature fumarole, named A-1, from 1954 (800 °C) to 1985 (336 °C), and from lower-temperature vents. Condensates were collected contemporaneously with the gas samples, and we reanalyzed ten of these samples, mostly from the A-1 vent, for 32 cations and three anions. Modeling using the thermochemical equilibrium program, SOLVGAS, shows that the gas samples are mild disequilibrium mixtures because they: (a) contain unequilibrated sedimentary CH 4 and NH 3; (b) have unequilibrated meteoric water; or (c) lost CO, either by air oxidation or by absorption by the sodium hydroxide sampling solution. SOLVGAS also enabled us to restore the samples by removing these disequilibrium effects, and to estimate their equilibrium oxygen fugacities and amounts of S 2 and CH 4. The restored compositions contain > 98% H 2O with minor to trace amounts of CO 2, H 2, HCl, SO 2, HF, H 2S, CO, S 2 and CH 4. We used the restored gas and condensate data to test the hypotheses that these time-series compositional data from the dome's fumaroles provide: (1) sufficient major-gas data to analyze long-term degassing trends of the dome's magma-hydrothermal system without the influence of sampling or contamination effects; (2) independent oxygen fugacity-versus-temperature estimates of the Showa-Shinzan dacite; (3) the order of release of trace elements, especially metals, from magma; and (4) useful information for assessing volcanic hazards. The 1954-1985 restored A-1 gas compositions confirm the first hypothesis because they are sufficient to reveal three long-term degassing trends: (1) they became increasingly H 2O-rich with time due to the progressive influx of meteoric water into the dome; (2) their {C}/{S}and{S}/{Cl} ratios decreased

  19. Japan.

    PubMed

    1987-02-01

    Japan is composed of 4 main islands and more than 3900 smaller islands and has 317.7 persons/square kilometer. This makes it one of the most densely populated nations in the world. Religion is an important force in the life of the Japanese and most consider themselves Buddhists. Schooling is free through junior high but 90% of Japanese students complete high school. In fact, Japan enjoys one of the highest literacy rates in the world. There are over 178 newspapers and 3500 magazines published in Japan and the number of new book titles issued each year is greater than that in the US. Since WW1, Japan expanded its influence in Asia and its holdings in the Pacific. However, as a direct result of WW2, Japan lost all of its overseas possessions and was able to retain only its own islands. Since 1952, Japan has been ruled by conservative governments which cooperate closely with the West. Great economic growth has come since the post-treaty period. Japan as a constitutional monarchy operates within the framework of a constitution which became effective in May 1947. Executive power is vested in a cabinet which includes the prime minister and the ministers of state. Japan is one of the most politically stable of the postwar democracies and the Liberal Democratic Party is representative of Japanese moderate conservatism. The economy of Japan is strong and growing. With few resources, there is only 19% of Japanese land suitable for cultivation. Its exports earn only about 19% of the country's gross national product. More than 59 million workers comprise Japan's labor force, 40% of whom are women. Japan and the US are strongly linked trading partners and after Canada, Japan is the largest trading partner of the US. Foreign policy since 1952 has fostered close cooperation with the West and Japan is vitally interested in good relations with its neighbors. Relations with the Soviet Union are not close although Japan is attempting to improve the situation. US policy is based on

  20. Japan.

    ERIC Educational Resources Information Center

    Jones, Savannah C.

    Materials for a secondary level, interdisciplinary social studies course on Japan are divided into introductory information, 14 classroom units, and study and evaluation materials. Introductory material includes lists of objectives and skills, an outline of Japanese history, and an explanation of Japan's name and flag. The units cover the…

  1. Japan

    ERIC Educational Resources Information Center

    Hawkins, John N.

    1986-01-01

    Analyzes the intergroup relations in Japanese society and Japan's educational system. Challenges the view that Japan is a homogeneous society by presenting the various forms of discrimination against Koreans, Ainu, and the burakumin. Suggests that despite ostracism and isolation, groups can affect public policy and achieve social advancement. (SA)

  2. Development of low noise cosmic ray muon detector for imaging density structure of Usu Volcano, Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Kusagaya, T.; Tanaka, H.; Taketa, A.; Oshima, H.; Maekawa, T.

    2012-12-01

    We are developing low noise cosmic ray muon detector to image a density structure of Usu Volcano, Hokkaido, Japan by muon radiography. Intensity of cosmic ray muon penetrating through the object is expressed as a function of the product of muon path length and density along muon path. And, the intensity of penetrating muon steeply decreases if muon path length becomes longer or density along muon path becomes larger. The detector that we are developing is called hodoscope that consists of multiple Position Sensitive Detectors (PSDs). A PSD has NxM grids consisting of N vertically aligned Scintillation Counters (SC: a plastic scintillator attached to a photo multiplier tube) and M horizontally aligned SCs. We can identify a muon path direction with two or more PSDs by connecting muon-detecting points in each PSD. But, Usu Volcano is so large that the intensity of penetrating muon becomes lower, and then noise rate becomes higher: the count of penetrating cosmic ray muon is estimated to be a few counts per month with the detector of which has the cross-section area of one square meter and the solid angle of 0.01 steradian. The noise is defined as a particle other than the muon penetrating the observed object such as electrons, photons, vertically arriving muons and so on. If noise rate becomes higher, the measured intensity of penetrating muon becomes higher than the theoretical intensity of that. Then we get a wrong result as if there were matter of lower density relative to real. So we need to develop a low noise detector. The ElectroMagnetic (EM) shower that consists of many electrons and photons is thought to be one of noise. When EM shower reaches the detector, each PSD detects arriving particles and detecting points are sometimes connected by a straight line. In that case, we cannot discriminate the penetrating muon from EM shower, and we count it as a muon event. This results noise. In order to discriminate the noise event, the use of more PSDs for our

  3. The effect of shear on permeability in a volcanic conduit: a case study at Unzen volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ashworth, James; Lavallée, Yan; Wallace, Paul; Lamur, Anthony; Kendrick, Jackie; Miwa, Takahiro

    2016-04-01

    The efficiency of outgassing at volcanoes is a function of permeability, and exerts a major influence on the type of eruptive behaviour exhibited. Understanding how shear affects the permeability profile across volcanic conduits is therefore a key part of understanding volcanic processes and the associated hazards. During the final months of the 1990-1995 eruption of Unzen volcano in southern Japan, extrusion of a dacite spine followed a period of endogenous dome growth. Many of the resulting formations are relatively accessible, allowing for the study of a variety of associated deformation phenomena. One of these formations, a ~6 m wide block, is a section of the extruded spine, that forms the basis for this study on shallow conduit processes. It displays a textural gradation from highly sheared rock to rock with negligible deformation, and is bounded at the high shear end by an agglutinated block of gouge that is thought to represent the conduit margin. A multi-faceted approach was taken to investigate the variation of permeability across the spine and its implications for processes occurring within the conduit. The permeability was measured at several points along the exposed surface of the spine transect using a field permeameter. Sample blocks from four of these locations were collected and tested in the lab using a hydrostatic pressure vessel water-flow permeameter and categorized as: gouge; highest shear; moderate shear; negligible shear. Each block was tested in three orthogonal axes: one perpendicular to observed shear; and two in the plane of shear. For each of these rocks, permeability and porosity measurements were made at a wide range of effective pressures (5 to 100 MPa), using a controlled upstream/downstream pore pressure gradient of 0.5 MPa (at an average pore pressure of 1.25 MPa). Thin sections of each sample were also taken prepared and analysed to describe the primary microstructures controlling the permeability of the rock. Textural analysis

  4. Andesite Magmas are Produced along Oceanic Arcs where the Crust is Thin: Evidence from Nishinoshima Volcano, Ogasawara Arc, Japan

    NASA Astrophysics Data System (ADS)

    Tamura, Y.; Ishizuka, O.; Sato, T.; Nichols, A. R.

    2015-12-01

    The incentive for this study is the ongoing explosive eruption of Nishinoshima volcano, located about 1,000 km south of Tokyo along the Ogasawara (Bonin) Arc. The straightforward but unexpected relationship presented here relates crustal thickness and magma type in the Izu-Ogasawara Oceanic Arc. Volcanoes along the Ogasawara segment of the arc, which include Nishinoshima, are underlain by thin crust (16-21 km)—in contrast to those along the Izu segment, where the crust is ~35 km thick. Interestingly, andesite magmas are dominant products from the former volcanoes and mostly basaltic lavas erupt from the latter. Why and how do volcanoes on the thin crust erupt andesite magmas? An introductory petrology textbook might answer this question by suggesting that, under decreasing pressure and hydrous conditions, the liquidus field of forsterite expands relative to that of enstatite, with the result that, at some point, enstatite melts incongruently to produce primary andesite melt. According to the hypothesis presented here, however, rising mantle diapirs stall near the base of the oceanic arc crust at depths controlled by the thickness of the overlying crust. Where the crust is thin, as along the Ogasawara segment of the arc, pressures are relatively low, and magmas produced in the mantle wedge tend to be andesitic. Where the crust is thick, as along the Izu segment, pressures are greater, and only basaltic magmas tend to be produced. To examine this hypothesis, JAMSTEC cruise NT15-E02 on the R/V Natsushima took place from 11 June to 21 June 2015 to Nishinoshima. It's present island has an elevation of only ~150 m, but its submarine flanks extend to ocean depths of 2,000-3,000 m, so the great bulk of the volcano is submarine and yet-to-be explored. We present the new hypothesis and its evidence from Nishinoshima based on the primitive lavas collected from the submarine parts of the volcano.

  5. PREFACE: Atomic Spectra and Oscillator Strengths (ASOS9) Atomic Spectra and Oscillator Strengths (ASOS9)

    NASA Astrophysics Data System (ADS)

    Wahlgren, Glenn M.; Wiese, Wolfgang L.; Beiersdorfer, Peter

    2009-05-01

    For the first time since its inaugural meeting in Lund in 1983, the triennial international conference on Atomic Spectroscopy and Oscillator Strengths for Astrophysical and Laboratory Plasmas (ASOS) returned to Lund, Sweden. Lund has been a home to atomic spectroscopy since the time of Janne Rydberg, and included the pioneering work in laboratory and solar spectroscopy by Bengt Edlén, who presented the initial ASOS talk in 1983. The ninth ASOS was hosted by the Lund Observatory and Physics Department of Lund University, 7-10 August 2007, and was attended by 99 registrants. An encouraging sign for the field was the number of young researchers in attendance. This volume of Physica Scripta contains contributions from the invited presentations of the conference. For the first time, papers from the ASOS9 poster presentations have been made feely available online in a complementary volume of Journal of Physics: Conference Series. With these two volumes the character of ASOS9 is more evident, and together they serve as a review of the state of atomic spectroscopy for spectrum analysis and the determination of oscillator strengths and their applications. The goal of ASOS is to be a forum for atomic spectroscopy, where both the providers and the users of atomic data, which includes wavelengths, energy levels, lifetimes, oscillator strengths and line shape parameters, can meet to discuss recent advances in experimental and theoretical techniques and their application to understanding the physical processes that are responsible for producing observed spectra. The applications mainly originate from the fields of astrophysics and plasma physics, which includes fusion energy and lighting research. The oral presentations, all but one of which are presented in this volume, provided an extensive synopsis of techniques currently in use and those that are being planned. New to ASOS9 was the extent to which techniques such as cold, trapped atoms and molecules and frequency combs are

  6. Seismic activity near the Moriyoshi-zan volcano in Akita Prefecture, northeastern Japan: implications for geofluid migration and a midcrustal geofluid reservoir

    NASA Astrophysics Data System (ADS)

    Kosuga, Masahiro

    2014-12-01

    The 2011 off the Pacific coast of Tohoku (Tohoku-oki) earthquake caused increased seismicity in many inland areas in Japan. A seismic cluster north of the Moriyoshi-zan volcano in Akita prefecture, Tohoku District, is of interest in light of the contribution of geofluids to seismic activity. We observed a seismic cluster characterized by the migration of seismicity and reflected/scattered phases. We relocated hypocenters of the cluster using data from temporal observations and the hypoDD location technique, which significantly increased the hypocentral accuracy. We interpreted a complex spatiotemporal variation of seismicity in the cluster as the migration of pore fluid pressure from multiple pressure sources. The hydraulic diffusivity of the cluster was in the range of 0.01 to 0.7 m2/s and increased with time, implying that the migration of hypocenters accelerated after a pathway for fluids was formed by fracturing of the wall rock during the initial stage of seismic activity. A prominent feature of the seismograms is a reflected/scattered phase observed at stations around the volcano. We regard the phase as S-to- S scattered waves and estimated the location of the scatterers using a back-projection method. The scatterers are inferred to be located about 5 km northwest of the Moriyoshi-zan volcano, at an approximate depth of 13 km. The Moriyoshi-zan area is one of the source areas of deep low-frequency earthquakes that have been interpreted as events generated by the migration of geofluids. The depth of the scatterers is close to the upper limit of the depth at which low-frequency earthquakes occur. Thus, we interpret the observed scatterers to be a reservoir of geofluid that came from the uppermost mantle accompanying contemporaneous low-frequency earthquakes.

  7. Seismic activity near the Moriyoshi-zan volcano in Akita Prefecture, northeastern Japan: implications for geofluid migration and a midcrustal geofluid reservoir

    NASA Astrophysics Data System (ADS)

    Kosuga, M.

    2014-12-01

    The 2011 off the Pacific coast of Tohoku (Tohoku-oki) earthquake caused increased seismicity in many inland areas in Japan. A triggered seismic cluster north of the Moriyoshi-zan volcano in Akita prefecture, Tohoku District, is of interest in light of the contribution of geofluids to seismic activity. We observed an active seismic cluster characterized by the migration of seismicity and reflected/scattered phases. We relocated hypocenters of the cluster using data from temporal observations and the hypoDD location technique, which significantly increased the hypocentral accuracy. We interpreted a complex spatiotemporal variation of seismicity in the cluster as the migration of pore fluid pressure from multiple pressure sources. The hydraulic diffusivity of the cluster was in the range of 0.01 to 0.7 m2/s and increased with time, implying that the migration of hypocenters accelerated after a pathway for fluids was formed by fracturing of the wall rock during the initial stage of seismic activity. A prominent feature of the seismograms is a reflected/scattered phase observed at stations around the volcano. We regard the phase as S-to-S scattered waves and estimated the location of the scatterers using a back-projection method. The scatterers are inferred to be located about 5 km northwest of the Moriyoshi-zan volcano, at an approximate depth of 13 km. The Moriyoshi-zan area is one of the source areas of deep low-frequency earthquakes that have been interpreted as events generated by the migration of geofluids. The depth of the scatterers is close to the upper depth limit of low-frequency earthquakes. Thus, we interpret the observed scatterers to be a reservoir of geofluid that came from the uppermost mantle accompanying contemporaneous low-frequency earthquakes.

  8. Response of a hydrothermal system to magmatic heat inferred from temporal variations in the complex frequencies of long-period events at Kusatsu-Shirane Volcano, Japan

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.

    2005-01-01

    We investigate temporal variations in the complex frequencies (frequency and quality factor Q) of long-period (LP) events that occurred at Kusatsu-Shirane Volcano, central Japan. We analyze LP waveforms observed at this volcano in the period between 1988 and 1995, which covers a seismically active period between 1989 and 1993. Systematic temporal variations in the complex frequencies are observed in October-November 1989, July-October 1991, and September 1992-January 1993. We use acoustic properties of a crack filled with hydrothermal fluids to interpret the observed temporal variations in the complex frequencies. The temporal variations in October-November 1989 can be divided into two periods, which are explained by a gradual decrease and increase of a gas-volume fraction in a water-steam mixture in a crack, respectively. The temporal variations in July-October 1991 can be also divided into two periods. These variations in the first and second periods are similar to those observed in November 1989 and in September-November 1992, respectively, and are interpreted as drying of a water-steam mixture and misty gas in a crack, respectively. The repeated nature of the temporal variations observed in similar seasons between July and November suggests the existence of seasonality in the occurrence of LP events. This may be caused by a seasonally variable meteoritic water supply to a hydrothermal system, which may have been heated by the flux of volcanic gases from magma beneath this volcano. ?? 2005 Elsevier B.V. All rights reserved.

  9. Is uplift of volcano clusters in the Tohoku Volcanic Arc, Japan, driven by magma accumulation in hot zones? A geodynamic modeling study

    NASA Astrophysics Data System (ADS)

    George, Ophelia A.; Malservisi, Rocco; Govers, Rob; Connor, Charles B.; Connor, Laura J.

    2016-06-01

    In many volcanic arcs, the rate of tectonic uplift cannot be explained by lithospheric plate motion alone but may be associated with dynamic uplift. Buoyant forces associated with underplated magma bodies lift the upper crust and leads to relatively high rates of topographic change. One such region is northern Honshu, Japan, where Quaternary volcano clusters are spatially associated with uplifted crust and isostatic gravity anomalies. Axisymmetric inversion of Bouguer gravity data for the Sengan volcano cluster shows that these gravity anomalies can be modeled by 30 km radius bodies emplaced at ˜15 km depth. Axisymmetric, finite element models, generated using GTECTON, of a layered Earth representative of the Tohoku crust indicate that the deformation of these midcrustal intrusions produces elevated topography on the surface directly above the intrusion that is bounded by a shallow peripheral trough. The wavelengths of vertical deformation produced by these bodies are sensitive to the thickness of the models' elastic layer and relatively insensitive to the models' rheology. This suggests that the amplitude of the vertical deformation represents a trade-off between the size of the intrusion and the thickness of the elastic layer and is less strongly influenced by the rheology of the lithosphere into which the bodies are emplaced. Our results are consistent with hot zone and hot finger models for the arc and indicate that Tohoku Volcanic Arc features such as gravity anomalies and uplifted basement are related to crustal magma intrusions and hot zones rather than directly related to mantle processes.

  10. Earthquake clustering and seismic scattering possibly related to geofluid near the Moriyoshi-zan volcano in the Akita Prefecture, northeastern Japan

    NASA Astrophysics Data System (ADS)

    Kosuga, M.

    2012-12-01

    The great 2011 Off the Pacific coast of Tohoku (Tohoku-oki) Earthquake brought increased seismicity in many areas apart from the source fault. In the inland area of Tohoku district, induced seismicity is quite high in the Akita Prefecture located in the Japan Sea side. Seismic activity to the north of Moriyoshi-zan volcano is interesting in the light of contribution of geofluid to earthquake clustering and seismic scattering. The Moriyoshi-zan is a Quaternary volcano located to the west of the volcanic front of northeastern Japan. Induced seismic activity around the volcano started just after the occurrence of Tohoku-oki earthquake, while the clustering began from May 2011, about two months after the Tohoku-oki earthquake. Relocated hypocenters show two column-like clusters separated about 1 km to the southwest and to the northeast. The diameter and the height of both columns are similar, about 1 km and 3 km, respectively. The seismic activity started from the southwest and migrated to the northeast with a speed of about 10 m/day in the horizontal direction. Vertical migration was not obvious. A prominent feature of the seismogram is the existence of a later phase in the S-wave coda. To minutely investigate the nature of the later phase, we calculated the RMS envelopes of band-pass-filtered seismograms at center frequencies of 1, 2, 4, 8, and 16 Hz. Stacked envelopes delineate the shape of coda part. Amplitude increase is distinct in wide frequency ranges from 4 to 16 Hz, and in the horizontal components observed at a station located to the west-southwest and at a station to the east of the epicenter. At the closest station, the amplitude starts to increase about 1 s after the arrival of S-wave and lasts about 2 s in the lower frequency range of 4 Hz. On the other hand, the increase is abrupt about 1.5 s after the S-wave arrival and the duration is shorter in the higher frequency range of 16 Hz. Similar later phase has previously observed from an earthquake swarm

  11. Magma generation and evolution processes of calc-alkalic and tholeiitic suites in Azuma volcano, NE Japan - Sr isotope micro-analysis study of plagioclase phenocrysts

    NASA Astrophysics Data System (ADS)

    Takahashi, T.; Hirahara, Y.; Kimura, J.; Chang, Q.; Tatsumi, Y.

    2009-12-01

    Magma generation and evolution processes of island-arc tholeiitic (TH) and calc-alkalic (CA) suites in the NE Japan arc have been thought that the former is produced by fractional crystallization from mantle-derived basalt magma and the latter is formed by magma mixing between basic and felsic magmas. However, based on Sr isotope micro-analyses of plagioclase phenocrysts in basalt and andesite lavas from Zao volcano, Tatsumi et al. (2008) argued that TH basalt was formed by melting of lower-crustal amphibolite, and CA was formed by magma mixing between mantle-derived basalt magma and the crust-derived basaltic andesite to dacite magmas. We present another example from Azuma volcano in the NE Japan arc which verifies our model. Sr isotope micro-analyses were performed by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS, NEPTUNE coupled to 193nm excimer laser system) and the combined method of micro-milling and thermal ionization mass spectrometry (MM-TIMS, micro-mill system and TRITON). The sampling crater size of LA-ICP-MS and MM-TIMS are 0.2mm and 0.27mm in both diameter and depth, respectively. Inner part of plagioclase phenocrysts in TH basalts have narrow range in An% and Sr isotope ratios (80 ~ 95% and 0.7058 ~ 0.7062). In contrast, plagioclases in CA basalts and andesites have widely ranges in An% and Sr isotope ratio (48 ~ 94%, 0.7039 ~ 0.7056). This observed variations are similar to that found in Zao samples, except that Sr isotope ratio is overall higher than that in Zao (Zao TH: 0.7043 ~ 0.7045, Zao CA: 0.7035 ~ 0.7045). We conclude that the magma generation and evolution model proposed by Tatsumi et al. (2008) is applicable to the Azuma TH and CA suites. Difference in the Sr isotope ratio of plagioclase between Azuma and Zao, particularly found in each TH suite lavas, can be explained by the difference in crust composition beneath the volcanoes.

  12. The Fukuyama volcanic rocks: Submarine composite volcano in the Late Miocene to Early Pliocene Akita-Yamagata back-arc basin, northeast Honshu, Japan

    NASA Astrophysics Data System (ADS)

    Yagi, Masahiko; Ohguch, Takeshi; Akiba, Fumio; Yoshida, Takeyoshi; Tiba, Tokiko

    2009-10-01

    The Fukuyama Volcanic Rocks are composed of pyroxene andesite (FKV-1), hornblende-pyroxene andesite (FKV-2), biotite-hornblende dacite (FKV-3) and volcaniclastic debris-flow deposits and/or turbidites. FKV-1, FKV-2 and FKV-3 are medium-K calc-alkaline rocks depleted in Nd, similar to other back-arc volcanic rocks of the northeast Japan arc and constitute a dome cluster at Fukuyama. Volcaniclastic beds surround the dome cluster and thin and fine upwards. The predominant clast type in the volcaniclastic beds changes upwards from pyroxene andesite, through hornblende-pyroxene andesite, to biotite-hornblende dacite, consistent with the stratigraphic relationships of FKV-1, FKV-2 and FKV-3 lavas. All the siltstones inter-bedded with the volcaniclastic beds and overlying the whole succession contain diatom fossils indicative of the lower part of the Thalassionema schraderi zone (7.8 Ma to 8.5 Ma), compatible with the isotopic ages of FKV-1, FKV-2 and FKV-3. The Fukuyama volcano has a total eruption volume of 60-100 km 3, with a lifetime of the order of 10 5 years, as typically observed for volcanoes in the present back-arc region of northeast Honshu. FKV-1 erupted in deep water and partly disintegrated into hyaloclastite breccias due to direct contact with water. FKV-2 lava repeatedly effused over the FKV-1 lava and produced a volcanic apron of breccias that eventually grew above wave base and was eroded by wave action. The magma of FKV-3 was probably hydrous as it contains biotite and hornblende. The FKV-3 magma could have explosively erupted from a shallow-water dome or vent emergent above the wave base, followed by growth of a degassing lava dome. Repose between eruptions allowed accumulation of silt, and after the Fukuyama eruptions ceased silt entirely mantled the volcano. A small magma supply rate perhaps allowed a relatively long period of quiescence between eruptions of FKV-1, FKV-2 and FKV-3 magmas, resulting in abrasion and reworking of volcanic fragments and

  13. Continuous survey of color and glass composition of ash particles by automatic sampling system at Sakurajima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Shimano, T.; Iguchi, M.; Miki, D.

    2013-12-01

    Activities at many subaerial volcanoes in subduction regions are characterized by ash emissions. Sakurajima volcano is also characterized by long-term successive ash emission such as vulcanian and strombolian eruptions that show many transitional features in eruption types, intensity of explosion or seismicity, amount and grain size of ash, height of plume, duration and interval of eruption, etc. In contrast, however, Plinian eruptions have occurred several times even in historical age, such as the 1914 eruption. In 2006, Showa crater of Sakurajima volcano became active since the 1946 eruption that similar ash emitting activity for several years evolved into effusion of large amount of lava. One of the aims of our study is to clarify how eruptions evolve into such larger eruptions from quiescent phase or moderate ash emission. We carried out continuous survey of ash particles of ash emitting eruptions, and here we report some results to reveal and understand transitional features of ash emitting activity. We started collection of ash at Sakurajima volcano in 2008 by establishing automatic sampling system. We developed mobile unmanned apparatus that enables continuous sampling of ash fall, and have been successful in daily collection of samples for five years at a locality 2.3 km from active vent, thus we have collected more than 1500 samples. The temporal change in daily amount of ash fall at this site was consistent with that estimated monthly by manned survey around this volcano. We found several types of ash particles in each of these samples where crystalline and glassy particles, in terms of groundmass crystallinity, are dominant types. We have carried out some analyses that characterize ash samples. Although petrological features are rather complex, chemical composition of matrix glass of particles and color of bulk ash sample in terms of photochrometry show systematic temporal changes in order of date that may be correlated with some geodetic observations

  14. A study of the Taisho lahar generated by the 1926 eruption of Tokachidake Volcano, central Hokkaido, Japan, and implications for the generation of cohesive lahars

    NASA Astrophysics Data System (ADS)

    Uesawa, Shimpei

    2014-01-01

    Understanding the generation mechanisms of lahars is important for improving volcanic hazard assessments. The Taisho lahar (TL) was generated during the 1926 eruption of Tokachidake Volcano, Japan, and was considered a typical snowmelt lahar caused by the runout of hot debris onto a snow-covered slope. A similar mechanism produced a huge mud flow during the 1985 eruption of Nevado del Ruiz, Colombia. However, the origin of water in such lahars remains a controversial topic because the calculated water mass is based on the assumption that all of the snow on the runout area of the TL was melted, although this is much less than the estimated water volume in the TL estimated by previous studies. I have re-examined proximal deposits of the TL and their paleomagnetic characteristics in order to better understand the eruption sequence and formation of the TL. The TL produced two debris avalanche deposits and a surge-like deposit that had relatively high emplacement temperature (~ 350 °C). The deposits are composed of hydrothermally altered andesitic gravel, sand and mud. The high clay content (3-5 wt.% clay in the < 2 mm fraction) and sedimentary characteristics indicate that the flow was a cohesive lahar, most likely induced by collapse of a hydrothermally altered pyroclastic cone (hypocenter). The presence of the surge deposit indicates that the TL was not caused by simple collapse of a cinder cone but by a phreatic explosion that resulted in sector collapse. This suggests that the hydrothermal system was related to the 1926 eruption. The present-day volcano has a large hydrothermal system (1 × 106 m3 water) beneath the active crater. This study indicates that hydrothermal system explosions can trigger cohesive lahars that contain both snow melt and hydrothermal pore water, and this indicates the need to monitor hydrothermal systems.

  15. Explosion Energy of the 2004 Eruption of the Asama Volcano, Central Japan: Inference From Ionospheric Disturbances Observed by a Dense GPS Array

    NASA Astrophysics Data System (ADS)

    Heki, K.

    2006-12-01

    Ionospheric Total Electron Content (TEC) can be easily measured as the phase differences of the L1 and L2 band carrier waves from Global Positioning System (GPS) satellites. Ionospheric disturbances measured as TEC changes have been contributing to not only solar-terrestrial studies but also solid earth geophysics, e.g. constraining the source process of the 2004 Sumatra Earthquake (Heki et al., JGR, 2006). Here I present a new application of GPS-TEC, i.e. estimation of the explosion energy of a volcanic eruption (Heki, GRL, 2006). The Asama Volcano, Central Japan, started eruptive activity at 11:02 UT on September 1, 2004, with a vulcanian explosion associated with strong airwaves. The Japanese dense GPS array GEONET recorded ionospheric disturbances as N-shaped changes in TEC approximately 12 minutes after the eruption. The disturbance had a period of 1.25 minutes and propagated as fast as about 1.1 km/s, suggesting its origin as the acoustic wave generated by the explosion. By comparing the disturbance amplitudes with those by a surface mine blast with a known energy (Calais et al., GJI, 1998), the overall Asama explosion energy is inferred to be equivalent to 1.2e14 Joule, about one third of the energy reported for the 1938 eruption (Minakami, BERI, 1942). Energy of the airwave can be estimated following Johnson (JVGR, 2003), assuming that the disturbance is a part of the spherical wave propagated from the volcano. We thus obtained the value 9.0e6 Joule, a typical value of airwave energies associated with volcanic eruptions. This new technique would complement past methods based on observations of mass deficits, near-field measurements of airwaves, etc, and may contribute to mitigation of volcanic hazards.

  16. A heating process of Kuchi-erabu-jima volcano, Japan, as inferred from geomagnetic field variations and electrical resistivity structure

    NASA Astrophysics Data System (ADS)

    Kanda, W.; Utsugi, M.; Tanaka, Y.; Hashimoto, T.; Fujii, I.; Hasenaka, T.; Shigeno, N.

    2009-12-01

    Since August 2000, we have recorded the total intensity of the geomagnetic field at the summit area of Kuchi-erabu-jima volcano, where phreatic eruptions repeatedly occurred. Prominent variations in the geomagnetic field have been observed since 2001 in concordance with the elevated volcanic activity as a result of the time series analysis performed to extract the volcanomagnetic variations. The obtained variations indicate thermal demagnetization of the subsurface around the presently active crater. The demagnetization source for the early variations until summer 2002 was roughly estimated at 200 m below sea level. For the variations after 2003, the source was modeled on the basis of the expansion of a uniformly magnetized ellipsoid. The modeling result showed that the source is located at 300 m above sea level beneath the crater. We carried out an audio-frequency magnetotelluric survey with the aim of obtaining a relation between the demagnetization source and the shallow structure of the volcano. A two-dimensional inversion applied to the data detected two good conductors, one of which is thin and restricted to the region near the ground surface around the summit area, while the other extends over the edifice at depths between 200 and 800m. These conductors are regarded as clay-rich layers with low permeability, which were assumed to be generated through hydrothermal alteration. The demagnetization source for the early variations is located at the lower part of the deep conductor and the source after 2003 lies between the two conductors, where groundwater is considered to be abundant. Based on these results, as well as on seismological, geodetic, and geochemical information, we propose a heating process of the Kuchi-erabu-jima volcano. At the early stage, high-temperature volcanic gases supplied from the deep-seated magma remained temporarily at the level around the lower part of the less permeable deep conductor since the ascent path had not yet been

  17. He, N and C isotopes and fluxes in Aira caldera: Comparative study of hydrothermal activity in Sakurajima volcano and Wakamiko crater, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Roulleau, Emilie; Sano, Yuji; Takahata, Naoto; Kawagucci, Shinsuke; Takahashi, Hirochi

    2013-05-01

    We investigate the degassing activity of an active submarine crater, Wakamiko, and an active sub-aerial volcano, Sakurajima, both located in Aira caldera, southern Kyushu, Japan. We provide 3He/4He, δ13C-CO2 and δ15N data for 15 hot springs, wells and bubbling gas from Sakurajima volcano, along with 3He/4He from seawater at four different sites for both Kagoshima bay and Wakamiko crater. We find a common magmatic 3He/4He ratio for Sakurajima and Wakamiko, 7.2 ± 0.8 Ra, which is consistent with 1) a mixing between air-saturated water (ASW) and MORB-type He, and 2) a common magmatic source located in the center of Aira caldera. Corrected 3He/4He, δ13C-CO2 and CH4/3He data for Sakurajima are correlated with the distance from the volcanic vent (Showa crater), which we attribute to crustal contamination and biogenic reaction. The low δ13C-CO2 values (- 10.1 ± 0.2‰ to - 13.7 ± 0.3‰) observed at Sakurajima may result from the addition of carbon from organic matter from basement rocks in magmatic source. After correction for air-derived nitrogen, we find δ15Nc values range between - 1.7‰ and + 4.3‰ which indicates that magmatic N is dominated by a sedimentary-derived component (up to 65.8%). We calculate Wakamiko fluxes of 4He (975 ± 228 mol/y), 3He (0.011 ± 0.003 mol/y), CO2 (184 ± 43 t/d), and heat (195 ± 22 MW). Our helium and heat fluxes are the first in situ fluxes ever reported for Wakamiko crater. All these Wakamiko fluxes are at least one order of magnitude lower than those observed for Sakurajima (CO2: 1800 t/d; 3He: 0.71 mol/y; heat: 2100 MW): degassing at Sakurajima volcano is much stronger than that at Wakamiko crater. The variation of Sakurajima CO2 flux with time, source (Minamidake or Showa crater) and eruptive activity, appears not to significantly affect the CO2 flux at Wakamiko crater, which is much more stable (132-307 t/d) during the last 30 years. This indicates that there is no link between Sakurajima and Wakamiko degassing

  18. Azimuthal Traveltime and Amplitude Anomalies of Tropospheric and Thermospheric Acoustic Waves From the Explosive Eruption of the Sakurajima Volcano in Japan

    NASA Astrophysics Data System (ADS)

    Watada, S.; Arai, N.; Murayama, T.; Iwakuni, M.; Nogami, M.; Oi, T.; Imanishi, Y.; Kitagawa, Y.

    2010-12-01

    With more than 20 microbarometers in a distance range from as small as 4 km to 1100 km, we observed the strongest explosive eruption since 2000 of the Sakurajima volcano, located at the southern end of the Kyushu Island in Japan. An MB2005 at 4-km away from the summit recorded one strong sharp acoustic signal with peak-to-peak amplitude 1200 Pa and duration 4 sec. This nearby microbarogram guarantees that no small eruption occurred with amplitude more than a few tens Pa within a day after this explosive eruption. At the I30H IMS array which is 1000 km away from the volcano, we observed a dispersed pressure wave train with duration 1 min and maximum amplitude 5 Pa and dominant periods 5-10 sec. Array analysis shows a tropospheric propagating infrasound from the azimuth of Sakurajima with an apparent velocity 0.345 km/s. All distant stations are nearly linearly aligned from Sakurajima to the I30H array and their azimuths are 37-65 deg. Within this small azimuth range, we observed a strong azimuthal anisotropy in traveltime and amplitude. The patterns of traveltime anomaly and amplitude are similar, earlier the arrival, larger the amplitude. This implies that these traveltime and amplitude anomalies are wave propagation origin and are likely caused by the wind, not by an asymmetric radiation pattern of the explosion source. More microbarograms including two MB2005s were running in the Honshu Island during the eruption but these records show little infrasound signals with amplitude more than a few Pa. There seems a clear areal boundary where infrasound was observed or not. Another prominent feature of waveforms is the multiple later phases reflected from the troposphere and the thermosphere. The record section of microbarograms recorded at less than 500 km from the volcano reveals nearly-equally time-separated later phases up to 5 bounces. The traveltime curves progressively increases the apparent velocity as the time increases and distance decreases, suggesting

  19. Heat discharge estimation using satellite remote sensing data on the Iwodake volcano in Satsuma-Iwojima, Japan

    NASA Astrophysics Data System (ADS)

    Urai, Minoru

    2002-03-01

    A series of heat discharges from the Iwodake volcano was estimated using nighttime Landsat TM data. The data includes heat discharge only from steaming ground and excludes fumarole, hot spring activities and others. The heat discharge was estimated at 40-80 MW from 1989 to 1993 using temperature distributions derived from Landsat TM band 6, and started to increase since 1995. From the error analysis, the true heat discharge will be in the range from -60% to +20% of the calculated discharge of this method. Two hot spots in the northeast to southwest direction correspond to the high temperature fumaroles seen in the temperature distributions derived from band 7. A new hot spot corresponds to a new degassing vent has been observed on the southern end of the summit crater since January 1992, and expanded to the same size as the other two hot spots since December 1993.

  20. The Lyman-alpha Solar Telescope for the ASO-S

    NASA Astrophysics Data System (ADS)

    Li, Hui

    2015-08-01

    The Lyman-alpha Solar Telescope (LST) is one of the payloads for the proposed Space-Borne Advanced Solar Observatory (ASO-S). LST consists of a Solar Disk Imager (SDI) with a field-of-view (FOV) of 1.2 Rsun, a Solar Corona Imager (SCI) with an FOV of 1.1 - 2.5 Rsun, and a full-disk White-light Solar Telescope (WST) with an FOV of 1.2 Rsun, which also serves as the guiding telescope. The SCI is designed to work at the Lyman-alpha waveband and white-light, while the SDI will work at the Lyman-alpha waveband only. The WST works both in visible (for guide) and ultraviolet (for science) white-light. The LST will observe the Sun from disk-center up to 2.5 solar radii for both solar flares and coronal mass ejections. In this presentation, I will give an introduction to LST, including scientific objectives, science requirement, instrument design and current status.

  1. Combined absolute and relative gravity measurement for microgravity monitoring in Aso volcanic field

    NASA Astrophysics Data System (ADS)

    Sofyan, Yayan; Nishijima, Jun; Yoshikawa, Shin; Fujimitsu, Yasuhiro; Kagiyama, Tsuneomi; Fukuda, Yoichi

    2014-05-01

    crater. Large residual gravity changes between the surveys of absolute and relative gravimeter are found at benchmarks around Nakadake crater. Keywords: Microgravity monitoring, Aso volcanic field References [1] Battaglia, M., J. Gottsmann, D. Carbone, and J. Fernandez, 2008, 4D volcano gravimetry: Geophysics, vol. 73 no.6, p. WA3-WA18.

  2. Izu-Oshima volcano, Japan: nine years of geochemical monitoring by means of CO_{2} soil diffuse degassing

    NASA Astrophysics Data System (ADS)

    Hernández, Pedro A.; Mori, Toshiya; Notsu, Kenji; Morita, Masaaki; Padrón, Eleazar; Onizawa, Shin'ya; Melián, Gladys; Sumino, Hirochicka; Asensio-Ramos, María; Nogami, Kenji; Pérez, Nemesio M.

    2016-04-01

    Izu-Oshima is a 15×9 km active volcanic island located around 100 km SSW of Tokyo. The centre of the island is occupied by a caldera complex with a diameter of 3 km. A large post-caldera cone known as Mt. Mihara is located at the south-western quadrant of the caldera. Izu-Oshima has erupted 74 times, consisting mainly in fissure eruptions, both inside and outside of the caldera. The last eruption of Izu-Oshima occurred in 1986. Since 2007, seven soil gas surveys have been carried out to investigate the spatial and temporal evolution of diffuse CO2 emission from this volcanic system and to identify those structures controlling the degassing process. Diffuse CO2 emission surveys were always carried out following the accumulation chamber method. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. The location of the CO2 anomalies has always shown a close relationship with the structural characteristics of the volcano, with most of the gas discharged from the rim of the summit crater. Temporal evolution of diffuse CO2 emission rate from Mt. Miharayama has shown a good temporal correlation with the seismicity recorded in and around Izu Oshima island during the period of study. The two peaks of seismic activity occur when highest CO2 diffuse emissions were computed, March 2007, August 2010 and July 2011, may be associated with fluid pressure fluctuations in the volcanic system due to the seismicity. In order to strength the contribution of deep seated gases to the diffuse emission, we performed carbon isotopic analysis of soil gas samples at selected sites during 2010, 2013 and 2015 surveys. At isotopic compositions lighter than ˜- 6‰ the soil CO2 effluxes were always low, while at heavier isotopic compositions an increasing number of points are characterized by relatively high soil CO efflux as a consequence of the addition of the hydrothermal CO2 source. Soil CO2 efflux peak values (xBackground) showed also a

  3. Progressive mixed-magma recharging of Izu-Oshima volcano, Japan: A guide to magma chamber volume

    NASA Astrophysics Data System (ADS)

    Ishizuka, Osamu; Taylor, Rex N.; Geshi, Nobuo; Oikawa, Teruki; Kawanabe, Yoshihisa; Ogitsu, Itaru

    2015-11-01

    To discover how magmas move and interact beneath an arc we have examined the temporal and spatial evolution of the largest Izu-Bonin frontal arc volcano Izu-Oshima and the adjacent Izu-Tobu field of backarc volcanoes. Extensive 14C ages and geochemical analysis of subaerial satellite cones as well as other effusives has enabled us to construct a well-constrained ∼ 14 ka record of Izu-Oshima volcanism. The geochemistry of Izu-Oshima is found to change systematically through the last 14 000 yr. Ba/La, Pb/Ce, 87Sr/86Sr, 143Nd/144Nd and 206Pb/204Pb all decrease between 10 ka and 5 ka before increasing between 5 ka and the present, while La/Yb and Nb/Zr show the reverse. These changes in composition match the addition of Izu-Tobu (backarc) magma to the Izu-Oshima plumbing system with a maximum of a 40% Izu-Tobu at around 5 ka. Progressive but asymptotically declining changes in composition through the 10-5 ka period are found to fit a model where pre-mixed magma is episodically added to, and mixed with, a chamber beneath Izu-Oshima. The 5-0 ka period reverses this trend, but is again progressive and declining, suggesting a switch to a progressive influx of pure Izu-Oshima frontal arc magma. Combining flux and eruption volume estimates with the observed geochemical mixing rates indicates that the accessible melt volume of the Izu-Oshima magma system is ∼ 16 km3. Interaction and pre-mixing between the fluid-dominated frontal arc melt and the sediment-bearing backarc magmas must occur at deeper levels within the arc crust. This deep reservoir receives a continuous feed from the frontal arc mantle, but may periodically intercept rising magmas from the backarc source to produce episodes of magma mixing on timescales of ∼ 5000 yr. This study demonstrates that interaction between frontal arc and backarc magma needs to be considered to achieve better understanding of material transfers and elemental budgets at subduction zones.

  4. Hokkaido, Japan

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Cities mingle with rugged hills and a dormant volcano in this image of Hokkaido, Japan. This three-dimensional image comes from observations made by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite on July 23, 2006. The view is toward the north and slightly east. Green indicates vegetation; beige and gray indicate bare ground, paved surfaces, or buildings; and dark blue indicates water. The water body at the top of the image is the Pacific Ocean. Now dormant, Mount Yotei is a stratovolcano--a symmetrical cone composed of alternating layers of hardened lava, solidified ash, and volcanic rocks ejected in previous eruptions. It reaches a height of 1,898 meters (6,227 feet), and its summit sports a 700-meter- (2,297-foot-) wide crater. Snow often caps this volcano, but in this summertime shot, the volcano's summit is snow-free. The volcano is also known as Ezo-Fuji for its resemblance to Mount Fuji. As angular patches of gray and beige indicate, urban areas surround the volcano, most notably the city of Kutchan to the northwest. Even when volcanoes remain active, people often settle close to them, drawn by benefits of good soil and mild climates that appear to outweigh the risks. NASA image by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  5. Conduit process in vulcanian eruptions at Sakurajima volcano, Japan: Inference from comparison of volcanic ash with pressure wave and seismic data

    NASA Astrophysics Data System (ADS)

    Miwa, T.; Toramaru, A.

    2013-01-01

    To elucidate the conduit processes controlling the amplitude of air pressure waves ( A pw) from vulcanian eruptions at the Sakurajima volcano, Japan, we examine ash particles emitted by eruptions preceded by swarms of low-frequency B-type earthquakes (BL-swarms). We measure the water content of glassy ash, an indicator of shallow magma storage pressure, and vesicle textures, such as vesicle number density (VND). These data allow us to reconstruct the shallow conduit by comparing vesicularity with inferred pressure, and therefore depth, of magma storage. The results show that VND increases with depth, implying formation of a dense, outgassed magma cap underlain by more-vesicular, less-outgassed, magma. The VND and water content in the glassy ash positively correlate with the duration of BL-swarms, suggesting that such seismic signals reflect upward migration of deep gas- and vesicle-rich magma. Finally, it is determined that A pw positively correlates with VND, suggesting that the amplitude of the air pressure waves is controlled by the amount of accumulated gas- and bubble-rich magma below the dense magma cap.

  6. Brownish discoloration of the summit crater lake of Mt. Shinmoe-dake, Kirishima Volcano, Japan: volcanic-microbial coupled origin

    NASA Astrophysics Data System (ADS)

    Ohsawa, Shinji; Sugimori, Kenji; Yamauchi, Hiroshi; Koeda, Tomoyuki; Inaba, Hiroaki; Kataoka, Yoshihisa; Kagiyama, Tsuneomi

    2014-05-01

    A drastic change in lake water color from blue-green to brown was observed in the summit crater lake of Mt. Shinmoe-dake, Kirishima Volcano about 8 months after its 2008 eruption. The color change lasted for about 2 months (April-June 2009). The discoloration was attributed to a brownish color suspension that had formed in the lake water. X-ray fluorescence and Fourier transform infrared analyses of a sample of the suspension identified schwertmannite (Fe8O8(OH)6(SO4)). A cultivation test of iron-oxidizing bacteria for the sampled lake water with lakebed sediment revealed that the crater lake hosts iron-oxidizing bacteria, which likely participated in schwertmannite formation. We suggest that pyrite (FeS2) provided an energy source for the iron-oxidizing bacteria since the mineral was identified in hydrothermally altered tephra ejected by the August 2008 eruption. From consideration of these and other factors, the brownish discoloration of the summit crater lake of Mt. Shinmoe-dake was inferred to have resulted from a combined volcanic-microbial process.

  7. The spectrum of basaltic feeder systems from effusive lava eruption to explosive eruption at Miyakejima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Geshi, Nobuo; Oikawa, Teruki

    2014-03-01

    Basaltic feeder systems exposed in the caldera wall of Miyakejima volcano are classified into three groups: (1) effusive feeders, (2) moderately explosive feeders, and (3) highly explosive feeders. The surface deposits and feeder systems reveal a wide variation in the explosivity of the eruptions that produced them, ranging from non-explosive lava effusions to violent explosive eruptions, despite the apparent lack of influence of external water. Effusive feeders are filled with coherent (non-fragmented) intrusive rock, indicating no significant fragmentation in the feeder system. The other two types of feeder systems consist of a coherent dike in their deeper part and a pyroclastic fill in their uppermost part. Their uppermost parts show an upward-flaring shape. The transition from coherent intrusion to pyroclastic fill in the feeder systems suggests underground fragmentation of the rising magma. The depth of the coherent-pyroclastic transition is deeper (20-150 m) in highly explosive feeders than in the moderately explosive feeders (<20 m), and coincides with the depth at which the system flares upwards. Presence of lithic fragments derived from the host rock in the products of the highly explosive feeder systems indicates the removal of the wall rock by explosive activity. This observation suggests that the fragmentation of rising magma promoted the enlargement of the feeder systems to form their upward-flaring shapes, by mechanical erosion and wall collapse.

  8. Implications of ASOS winds on regulatory dispersion modeling applications

    SciTech Connect

    Jones, W.B.; Brower, R.P.

    1998-12-31

    With the advent of the Automated Surface Observing System (ASOS) throughout the United States during the 1990`s, an unprecedented level of meteorological data is now available. For the first time, observations of standard meteorological variables are available on a minute-by-minute basis. As a result, ASOS has tremendously increased the real-time data available for both weather forecasting and aviation purposes. However, the affect of the ASOS method of data collection on the dispersion modeling community is less clear. Because the hourly data now being reported at most stations across the country are being gathered in a fundamentally different way than previously, it is prudent to examine the differences between hourly meteorological observations gathered before and after ASOS. This paper scrutinizes wind speed and direction data gathered at Baltimore-Washington International Airport and Washington Dulles International Airport and quantifies the differences. Wind data are critical in determining the transport and dispersion of pollutant plumes. Relationships between manually gathered wind data and ASOS wind data are examined. Finally, potential ramifications on dispersion modeling applications are discussed.

  9. Multiple-pressure-source model for ground inflation during the period of high explosivity at Sakurajima volcano, Japan - Combination analysis of continuous GNSS, tilt and strain data -

    NASA Astrophysics Data System (ADS)

    Hotta, Kohei; Iguchi, Masato; Ohkura, Takahiro; Yamamoto, Keigo

    2016-01-01

    We herein propose a three-pressure-source model for ground inflation with highly eruptive activity at the Showa crater of Sakurajima volcano, Japan. We applied a model of stacked spherical sources to continuous combined geodetic data from a global navigation satellite system, tilt and strainmeters. The data were recorded during ground inflation throughout an eruptive episode that began in October 2011 and ended in March 2012. Using a genetic algorithm, we obtained the locations and volumes of three sources. A pressure source analysis of ground inflation during the period from October 2011 to March 2012 revealed inflation sources to be located at a depth of 9.6 km beneath Aira caldera (A-source) and 3.3 km beneath Kita-dake (K-source), and a shallow deflation source is located at a depth of 0.7 km beneath Minami-dake (M-source). The A-source corresponds to the main magma reservoir at a depth of 10 km beneath the Aira caldera inferred by previous geophysical studies. The K-source is a-reservoir of Sakurajima volcano, where magma intrudes from the main magma reservoir beneath the Aira caldera during the first stage of eruptive activity. The M-source is the uppermost part of a conduit from the K-source to the summit and the Showa crater. Magma injection into the A-source started in mid-November 2011, instantly triggering the migration of increased volumes of magma from the A-source to the K-source. Approximately one month later, in mid-December 2011, an increased volume of magma started migrating from the K-source to the M-source and finally erupted at the surface. The accumulation rate for the A-source is comparable to the magma supply rate for the past 100 years (0.8 to 1.6 × 107 m3). The three-pressure-source model was applied to inflation events before the 2011 event in order to reconstruct the magma migration process. Applying our source model to earlier activity phases, we found that injected magma from the A-source remained at the K-source and a small amount of

  10. A Mechanism For Production Of Calc-alkalic And Tholeiitic Magma Series In Zao Volcano, NE Japan (II) - Sr Isotope Micro-analysis Of Plagioclase Phenocrysts

    NASA Astrophysics Data System (ADS)

    Takahashi, T.; Hirahara, Y.; Tatsumi, Y.; Kimura, J.; Ban, M.

    2006-12-01

    It was discussed from the investigation of bulk rock chemical compositions and isotopes ratio that the origin magma or material of calc-alkalic series (CA) and tholeiitic series (TH) from Zao volacano, NE Japan was several necessity (Hirahara et al., 2006). Consequently, we paid attention to Sr isotope ratio of phenocrystic minerals in volcanic rocks, because it can be thought to recorded such magmatic processes, and proposed a mechanism for producing these two magma series based on data obtained by Sr isotopic micro-analyses of plagioclase in volcanic rocks from Zao Volcano. The Sr isotope micro-analyses were performed by two methods. One is the Laser Ablation Multicollector Inductively Coupled Plasma Mass Spectrometry. The ablate crater size is 0.2mm. Other one is combined method of microdrilling and Thermal Ionization Mass Spectrometey. The microdrilling is the sampling technique of drilling a sample mechanically with a small drill and collecting the sample powder milled. The diameter at the tip of the drills used for sampling is 0.1 and 0.27mm. The collected sample powder was dissolved with acid, and Sr was separated using micro-columns Sr selective resin. Sr isotope measurement was carried out on the Thermal Ionization Mass Spectrometer. Core part of plagioclases in CA has widely An% and Sr isotope ratio (52 ~ 93 and 0.7035 ~ 0.7045), and there are divided into several types by the isotopical and compositional characteristics. Especially, plagioclase of most high An% (90 ~ 93) type in CA shows the lowest Sr isotope ratio (0.7035 ~ 0.7037). On the other hand, plagioclase in TH possesses relatively narrow range of An% and Sr isotope ratio (85 ~ 95 and 0.7042 ~ 0.7045), and there is a tendency that Sr isotope ratio slightly increase with decreasing An%. Results of Sr isotope micro-analyses show that CA formed by magma mixing between isotopically depleted basalt magma and isotopically enriched felsic magma. On the other hand, it shows that the primary basalt magma

  11. Mineralogical and Sulfur Isotopic Study on Volcanic Ash of the 2014 Eruption at Ontake Volcano, Central Honshu, Japan

    NASA Astrophysics Data System (ADS)

    Imura, T.; Minami, Y.; Ohba, T.; Takahashi, R.; Imai, A.; Hayashi, S.

    2015-12-01

    Ontake volcano erupted on 27th September 2014. Components in fallout samples were analyzed with microscope, XRD, and SEM-EDS. Pyrophyllite, smectite, muscovite, kaoline group minerals, quartz, cristobalite, tridymite, pyrite, alunite, gypsum and anhydrite were identified from bulk samples. Coarse ash fraction (> 125 µm) consists mainly of siliceous fragments that are intensely altered and contain pyrite and rutile. Weakly-altered dark-gray volcanic rock fragments are also contained. Fine fraction is abundant in euhedral free crystals of alunite and gypsum and aggregates of silica minerals. The 34S/32S ratios of bulk ash samples were analyzed for sulfur leached by water (water-soluble sulfate), gastric (HCl-soluble sulfate), and HNO3 (sulfide). Gastric and HNO3 leaching methods were applied to coarse fraction too. The bulk δ34SCDT compositions of water-soluble sulfate, HCl-soluble sulfate and sulfide were +14.7 ‰, +15.7 ‰, and -4.7 ‰, respectively. Those of HCl-soluble sulfate and sulfide in coarse fraction were +9.1 ‰ and -4.3 ‰, respectively. Paragenesis of quartz and pyrophyllite in single grain implies hydrothermal alteration by hot (> 230 °C), acidic fluid in the sub-volcanic system. The sulfur isotope geothermometry (Ohmoto and Rye, 1979) applied to the pair of water-soluble sulfate and bulk sulfide resulted in 306 °C. Similar temperature (ca. 296 °C) was estimated for the pair of HCl-soluble sulfate and sulfide in bulk ash. The mineralogy and sulfur isotopic study indicate that the 2014 Ontake eruption was derived from an acidic high-temperature (ca. 300 °C) sub-volcanic hydrothermal fluid. However, the estimated temperature for the pair of HCl-soluble sulfate and sulfide from coarse fraction resulted in higher temperature (ca. 482 °C). The coarse fraction preserved the past temperature record of the hydrothermal fluid, because the coarse lithic fragments were derived from pre-existing altered rocks.

  12. Imaging the hydrothermal system beneath the Jigokudani valley, Tateyama volcano, Japan: implications for structures controlling repeated phreatic eruptions from an audio-frequency magnetotelluric survey

    NASA Astrophysics Data System (ADS)

    Seki, Kaori; Kanda, Wataru; Ogawa, Yasuo; Tanbo, Toshiya; Kobayashi, Tomokazu; Hino, Yuta; Hase, Hideaki

    2015-01-01

    This study focuses on the results of an audio-frequency magnetotelluric (AMT) survey across the Jigokudani valley, Tateyama volcano, Japan, to investigate the spatial relationship between the distribution of electrical resistivity and geothermal activity and to elucidate the geologic controls on both its phreatic eruption history and recent increase in phreatic activity. The AMT data were collected at eight locations across the Jigokudani valley in September 2013, with high quality data obtained from most sites, enabling the identification of an underground 2D resistivity structure from the transverse magnetic (TM) mode data. The data obtained during this study provided evidence of a large conductive region beneath the surface of the Jigokudani valley that is underlain by a resistive layer at depths below 500 m. The resistive layer is cut by a relatively conductive region that extends subvertically toward the shallow conductor. The shallow conductive region is divided into an uppermost slightly conductive section that is thought to be a lacustrine sediment layer of an extinct crater lake containing hydrothermal fluids and a lower section containing a mix of volcanic gases and hydrothermal fluids. The low permeability of the clay zone means that the uppermost clayey sediments allow the accumulation of gases in the lower section of the conductive region, suggesting the existence of a cap structure. The deep resistive layer likely consists of units similar to the granitic rocks that are widely exposed throughout the Jigokudani valley. We suggest that the relatively conductive zone that separates these granitic rocks represents a high-temperature volcanic gas conduit, given that the most active fumarole in the Jigokudani valley lies directly along the trajectory of this path.

  13. Source mechanism of long-period events at Kusatsu-Shirane Volcano, Japan, inferred from waveform inversion of the effective excitation functions

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.; Chouet, B.A.

    2003-01-01

    We investigate the source mechanism of long-period (LP) events observed at Kusatsu-Shirane Volcano, Japan, based on waveform inversions of their effective excitation functions. The effective excitation function, which represents the apparent excitation observed at individual receivers, is estimated by applying an autoregressive filter to the LP waveform. Assuming a point source, we apply this method to seven LP events the waveforms of which are characterized by simple decaying and nearly monochromatic oscillations with frequency in the range 1-3 Hz. The results of the waveform inversions show dominant volumetric change components accompanied by single force components, common to all the events analyzed, and suggesting a repeated activation of a sub-horizontal crack located 300 m beneath the summit crater lakes. Based on these results, we propose a model of the source process of LP seismicity, in which a gradual buildup of steam pressure in a hydrothermal crack in response to magmatic heat causes repeated discharges of steam from the crack. The rapid discharge of fluid causes the collapse of the fluid-filled crack and excites acoustic oscillations of the crack, which produce the characteristic waveforms observed in the LP events. The presence of a single force synchronous with the collapse of the crack is interpreted as the release of gravitational energy that occurs as the slug of steam ejected from the crack ascends toward the surface and is replaced by cooler water flowing downward in a fluid-filled conduit linking the crack and the base of the crater lake. ?? 2003 Elsevier Science B.V. All rights reserved.

  14. Large-scale internal structure of the Sanbongi Fan-Towada Volcano, Japan: Putting the theory to the test, using GPR on volcaniclastic deposits

    NASA Astrophysics Data System (ADS)

    Gomez, Christopher; Kataoka, Kyoko S.; Tanaka, Kenji

    2012-06-01

    The Towada Caldera Volcano is located between the prefectures of Aomori and Akita — Northeast Honshu Island, Japan. The caldera, today filled by a lake, has produced 15,000 years ago a complex eruption emplacing an ignimbrite topped by the lake outburst flood deposit, through which the present Oirase River erodes. This flood deposit has shaped the geomorphologic feature named Sanbongi Fan, on which Towada City extends. This flood event hypothesis is mainly based on sedimentological and geomorphological evidences of floods mainly from outcrops retrieved from the Sanbongi Fan area. Because of the lack of extended outcrops - typical of the Japanese environment - the present paper has therefore put the theory to the test using GPR (Ground Penetrating Radar) radargram extending along a 640 m length. The GPR used for the survey was a Pulse-ekko-Pro with 50 MHz antennas, and the software Reflex was used to process the data. The radargrams have displayed a sole unit, which the GPR could not penetrate. It can be interpreted as the ignimbrite. On top of this deposit a series of subhorizontal layers, with the alternation between a backset and a foreset extends between 5 m and 3 m depth. Above 3 m, the units are regular and subhorizontal. The deposit is also characterized by the extensive presence of boulders, which are located along three bands: (1) on top of the ignimbrite; (2) in the units deposited by the outburst flood, between 3 and 5 m depths; (3) and in the units close to the surface, although part of these punctual elements are most certainly anthropogenic. Compared with the outcrops, the present research confirms that the material located above the ignimbrite material have been deposited by the outburst flood, creating large-sheet patterns, which have transported boulders. These sheets display backset and foreset patterns, depending on the position of the deposit, indicating flow pulsation or surges under a 'high-energy-flow' condition.

  15. Characterization of the Low-Temperature Pyroclastic Surge Occurred from AD1888 to 1900 in the volcanoes of Northeastern Japan Arc

    NASA Astrophysics Data System (ADS)

    Fujinawa, A.; Ban, M.; Kontani, K.

    2006-12-01

    Phreatic explosion and its accompanying low-temperature pyroclastic surge are, in general, good natural examples to examine the usefulness of the simulation results of the explosion experiments. Several phreatic explosions have been recorded at the volcanoes in the southern part of the NE Japan within a short period. We selected the Bandai 1888 and Adatara 1900, and additionally, Zao 1895 eruptions, to re-examine and to restructure the sequence and detailed nature of the eruption phenomena, by combining the old documents including the reports of newspapers with detailed field survey and facies analyses of the surge. Common geological and stratigraphical features among these pyroclastic surge deposits are revealed. These include: 1) the thickness of the deposits near the eruption center reaches several meters, whereas it decreases abruptly, resulting in apron-like deposits, only the deposit may last more than 1 km restrictedly along the valley, 2) massive facies are dominant in the proximal area with or without wood, broken chinaware and/or regolith at the base of the deposits, 3) fine and in some cases laminated ash deposits are dominant, and also in some cases pisolites are recognized in the distal area. These indicate that the presently studied surge events are essentially high-velocity, low-density, low-temperature and wet members of the pyroclastic density current clan. The estimated explosion energies and the volumes of the surge deposits are 2x1016 J and 10-2 km3 for Bandai 1888, and 6x1013 J and 3x10-4 km3 for Adatara 1900 eruptions, respectively, suggesting that the volume of pyroclastic surge originated from phreatic explosion roughly correlate positively with the explosion energy.

  16. Reconstruction of a phreatic eruption on 27 September 2014 at Ontake volcano, central Japan, based on proximal pyroclastic density current and fallout deposits

    NASA Astrophysics Data System (ADS)

    Maeno, Fukashi; Nakada, Setsuya; Oikawa, Teruki; Yoshimoto, Mitsuhiro; Komori, Jiro; Ishizuka, Yoshihiro; Takeshita, Yoshihiro; Shimano, Taketo; Kaneko, Takayuki; Nagai, Masashi

    2016-05-01

    The phreatic eruption at Ontake volcano on 27 September 2014, which caused the worst volcanic disaster in the past half-century in Japan, was reconstructed based on observations of the proximal pyroclastic density current (PDC) and fallout deposits. Witness observations were also used to clarify the eruption process. The deposits are divided into three major depositional units (Units A, B, and C) which are characterized by massive, extremely poorly sorted, and multimodal grain-size distribution with 30-50 wt% of fine ash (silt-clay component). The depositional condition was initially dry but eventually changed to wet. Unit A originated from gravity-driven turbulent PDCs in the relatively dry, vent-opening phase. Unit B was then produced mainly by fallout from a vigorous moist plume during vent development. Unit C was derived from wet ash fall in the declining stage. Ballistic ejecta continuously occurred during vent opening and development. As observed in the finest population of the grain-size distribution, aggregate particles were formed throughout the eruption, and the effect of water in the plume on the aggregation increased with time and distance. Based on the deposit thickness, duration, and grain-size data, and by applying a scaling analysis using a depth-averaged model of turbulent gravity currents, the particle concentration and initial flow speed of the PDC at the summit area were estimated as 2 × 10-4-2 × 10-3 and 24-28 m/s, respectively. The tephra thinning trend in the proximal area shows a steeper slope than in similar-sized magmatic eruptions, indicating a large tephra volume deposited over a short distance owing to the wet dispersal conditions. The Ontake eruption provided an opportunity to examine the deposits from a phreatic eruption with a complex eruption sequence that reflects the effect of external water on the eruption dynamics.

  17. Subduction influence of Philippine Sea plate on the mantle beneath northern Kyushu, SW Japan: An examination of boron contents in basaltic rocks

    NASA Astrophysics Data System (ADS)

    Miyoshi, Masaya; Fukuoka, Takaaki; Sano, Takashi; Hasenaka, Toshiaki

    2008-03-01

    Northern Kyushu, characterized by the subduction of two oceanic slabs (a hot Shikoku basin and a cold Philippine Sea plate) beneath the Eurasian plate, forms a complex portion of Southwestern Japan arc. In order to evaluate the effect of slab-derived fluids from these two contrasting oceanic plates, we determined the boron (B) contents in basaltic rocks from ten volcanoes and three old volcanic fields which erupted since 11 Ma. Since B is distinctly concentrated into slab-derived fluids among the earth's materials, we attempted to estimate the influences of subduction on the sub-arc mantle composition from the interpretation of the B data in basaltic rocks. Old (11-6 Ma) basaltic rocks contain low ratios of B/Sm (0.5-1.3), B/Zr (0.02-0.05) and B/Nb (0.2-0.5), suggesting little influence of subduction. Similarly, backarc basaltic rocks occurring throughout the observed period show little influence of subduction. In contrast, volcanic products from young Aso volcano, located at the volcanic front, show a strong influence of subduction, as indicated by the high B/Sm (1.6-4.3), B/Zr (0.07-0.16) and B/Nb (1.4-3.7) ratios. After 6 Ma, the volcanic arc segment containing Aso volcano is associated with the subduction of the cold Philippine Sea plate; hence a B-rich fluid was probably added to the sub-arc mantle. However, Yufu, Tsurumi and Kuju volcanoes, which are located at the same volcanic front, show small B/Sm (0.9-1.9), B/Zr (0.04-0.07) and B/Nb (0.5-0.9) ratios. This implies that the subduction of the hot Shikoku basin released fluids from the slab at shallow depths; therefore it is depleted of B and other subduction components by the time it reaches the volcanic front.

  18. Shaking up volcanoes

    USGS Publications Warehouse

    Prejean, Stephanie G.; Haney, Matthew M.

    2014-01-01

    Most volcanic eruptions that occur shortly after a large distant earthquake do so by random chance. A few compelling cases for earthquake-triggered eruptions exist, particularly within 200 km of the earthquake, but this phenomenon is rare in part because volcanoes must be poised to erupt in order to be triggered by an earthquake (1). Large earthquakes often perturb volcanoes in more subtle ways by triggering small earthquakes and changes in spring discharge and groundwater levels (1, 2). On page 80 of this issue, Brenguier et al. (3) provide fresh insight into the interaction of large earthquakes and volcanoes by documenting a temporary change in seismic velocity beneath volcanoes in Honshu, Japan, after the devastating Tohoku-Oki earthquake in 2011.

  19. The Role of Philippine Sea Plate to the Genesis of Quaternary Magmas of Northern Kyushu Island, Japan, Inferred from Along-Arc Geochemical Variations

    NASA Astrophysics Data System (ADS)

    Shibata, T.; Yoshikawa, M.; Itoh, J.; Ujike, O.; Miyoshi, M.; Takemura, K.

    2013-12-01

    Quaternary volcanoes on Kyushu Island comprise volcanoes Himeshima, Futagoyama, Yufu-Tsurumi, Kuju, Aso, Kirishima and Sakurajima from north to south alongstrike the volcanic front. Adakitic lavas are observed from Yufu-Tsurumi and Kuju volcanoes in northern Kyushu (Kita et al., 2001; Sugimoto et al., 2007), whereas no Quaternary adakites were observed at Aso (e.g., Hunter, 1998) and the volcanoes south of Aso along the entire Ryukyu arc. Sugimoto et al. (2007) suggested that the trace element and Sr, Nd, and Pb isotopic compositions of adakitic magmas from Yufu-Tsurumi volcano indicate derivation of the magmas by partial melting of the subducting PSP. In contrast, Zellmer et al. (2012) suggested that these adakites may have formed by fractional crystallization of mantle-derived mafic magmas within the garnet stability field in the crust. The Honshu-Kyushu arc transition is a particular favorable setting to address these controversial models for the origin of the adakitic lavas, because of the potential relationship between the PSP materials and the alongstrike variation of the lava chemistry. The Palau-Kyushu ridge divides the oceanic crust of the PSP into northeastern and southwestern segments with ages of 26-15 (Shikoku Basin) and 60-40 Ma (West Philippine Basin), respectively (Mahony et al., 2011). Although there are no clear plate images beneath northern Kyushu, the northern extension of the Palau-Kyushu ridge potentially corresponds to the boundary between the SW Japan and Ryukyu arcs. If adakite genesis was related to the subducted slab rather than the overlying crust, then the spatial distribution of Quaternary adakites should correlate with the age of the subducted PSP. In order to test such correlation and elucidate the petrogenesis of the northern Kyushu adakites, we compiled major and trace elements and Sr-Nd-Pb isotope ratios from volcanoes along the arc front that includes the transition from adakitic to non-adakitic arc volcanism. Comprehensive

  20. Nyiragonga Volcano

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image of the Nyiragonga volcano eruption in the Congo was acquired on January 28, 2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters about 50 to 300 feet ), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    Image: A river of molten rock poured from the Nyiragongo volcano in the Congo on January 18, 2002, a day after it erupted, killing dozens, swallowing buildings and forcing hundreds of thousands to flee the town of Goma. The flow continued into Lake Kivu. The lave flows are depicted in red on the image indicating they are still hot. Two of them flowed south form the volcano's summit and went through the town of Goma. Another flow can be seen at the top of the image, flowing towards the northwest. One of Africa's most notable volcanoes, Nyiragongo contained an active lava lake in its deep summit crater that drained catastrophically through its outer flanks in 1977. Extremely fluid, fast-moving lava flows draining from the summit lava lake in 1977 killed 50 to 100 people, and several villages were destroyed. The image covers an area of 21 x 24 km and combines a thermal band in red, and two infrared bands in green and blue.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the

  1. The evaluation of ASOS for the Kennedy Space Center's Shuttle Landing Facility

    NASA Technical Reports Server (NTRS)

    Yersavich, Ann; Wheeler, Mark; Taylor, Gregory; Schumann, Robin; Manobianco, John

    1994-01-01

    This report documents the Applied Meteorology Unit's (AMU) evaluation of the effectiveness and utility of the Automated Surface Observing System (ASOS) in terms of spaceflight operations and user requirements. In particular, the evaluation determines which of the Shuttle Landing Facility (SLF) observation requirements can be satisfied by ASOS. This report also includes a summary of ASOS' background, current configuration and specifications, system performance, and the possible concepts of operations for use of ASOS at the SLF. This evaluation stems from a desire by the Air Force to determine if ASOS units could be used to reduce the cost of SLF meteorological observations.

  2. Time Variation of Seismic Anisotropy, Stress and Cracks on Active Volcanoes (Invited)

    NASA Astrophysics Data System (ADS)

    Savage, M. K.

    2013-12-01

    We summarize measurements of seismic anisotropy and its relation to other geophysical measurements of stress and cracks on eleven active volcanoes; Unzen (Unz), Sakurajima (Sak), Aso, Asama (Asm) and Kirishima (Kir) in Japan; Okmok (Okm) in Alaska, Ruapehu (Rua) and Tongariro (Ton) in New Zealand, Soufriere Hills (Sou) in Montserrat, Kilauea (Kil) in Hawaii and Piton de la Fournaise (PdF) in La Reunion. We used the MFAST shear wave splitting computer code, an objective code that is fully automatic except for the S arrival pick. Fast polarization directions (phi) should be parallel to cracks and hence the maximum horizontal stress direction. Time delays (dt) increase with path length and percent anisotropy, usually related to crack density. Where possible we used S waves from deep earthquakes to ensure that the movement of the earthquakes was not correlated with the volcanic activity. At some volcanoes we used families of repeating events with similar waveforms and at most volcanoes we also computed splitting at earthquakes local to the volcano. We compared the phi and dt variation in time to eruption occurrences and to other available parameters including seismicity rate, b-values, focal mechanisms, isotropic velocity changes from noise cross-correlation, Vp/Vs ratios, Geodetic measurements such as GPS and tilt, and gas flux. All volcanoes had some stations with excellent shear wave arrivals that yielded measureable splitting. Individual measurements showed scatter in most areas, but at most of the volcanoes, moving averages of phi or dt (or both) yielded time variations that correlated with other measurements related to volcanic activity or to stress changes or changes in crack-filling material such as gas flux. The multiplet studies did not yield slowly varying splitting but instead showed distinct jumps in splitting parameters at various times, which appears to be caused in part by cycle skipping. Time resolution of changes depends on the seismicity available

  3. Bubble Coalescences Found in a Scoria from 2014-2015 Aso Eruption

    NASA Astrophysics Data System (ADS)

    Namiki, A.

    2015-12-01

    November 2014, Aso Volcano resumed the eruption after approximately 20 years quiescence. The main activity was ash eruption with silent large plumes, but Strombolian eruption of spouting scoriae without ash also was observed. Most of scoriae are highly vesiculated, and have low density (Yokoo and Miyabuchi, 2015). In order to understand the evolution of bubble texture, I observed the scoriae in three methods, the microscope, CT scan, and SEM those can observe different scales of 10 mm, 1 mm, 10μm, respectively. The microscope images show that larger bubbles (10mm) are surrounded by small bubbles (< 1mm), which shows elongated structure and suggesting that deformed by the large bubbles. CT images also show that larger bubbles (1mm) are surrounded by small bubbles (100μm). SEM images show that the bubble film thickness is approximately 1μm or less. According to the observation of pumices in other volcanoes, the typical bubble film thickness is estimated to be about 0.1-1μm (Nguyen, et al, 2013). In general, the volume fraction of bubbles and number density determine the thickness of the bubble films. For a smaller number density of bubbles, bubble size becomes larger in a same bubble volume fraction, so that the bubble film becomes thicker. In other words, the bubble films in the bubbly magma with a large number density reach the minimum thickness at a lower degree of bubble fraction. As a result, the bubble films rupture, or by coagulation, the larger bubble assimilates small bubbles. By the increase of the bubble size, thickness of the bubble film increases to be larger than the minimum thickness of 1μm. If such coalescences occur, the bubble size must have variety. From the varying bubble size and 1 1μm film thickness of scoriae, I infer that bubble coalescence occurred in the ascending bubbly magma in the conduit.

  4. Nicaraguan Volcanoes

    Atmospheric Science Data Center

    2013-04-18

    article title:  Nicaraguan Volcanoes     View Larger Image Nicaraguan volcanoes, February 26, 2000 . The true-color image at left is a ... February 26, 2000 - Plumes from the San Cristobal and Masaya volcanoes. project:  MISR category:  gallery ...

  5. Magma ascent mechanism during the 2011 eruption of Shinmoedake, Kirishima Volcano, Japan, deduced from the analysis of morphology and texture of volcanic ashes

    NASA Astrophysics Data System (ADS)

    Oishi, M.; Miwa, T.; Geshi, N.; Shinohara, H.; Vinet, N.

    2013-12-01

    The eruption styles can change over a short period of time during volcanic eruptions, in response to changes of magma ascent rate, outgassing, or crystallization in shallow conduits, which affect explosivity. Petrological characteristics of volcanic ashes, in particular their vesicularity and crystallinity, record the physical conditions that occur in the conduits, together with information on the eruption style, and can be used to investigate the magma ascent and storage processes prior to eruption. This study describes the particle componentry, external morphology, and internal texture (e.g. vesicularity; crystallinity) of volcanic ashes derived from the 2011 eruption of Shinmoedake, Kirishima Volcano, Japan, and their time series. The eruption style changed gradually throughout the volcanic sequence, including subplinian and vulcanian eruptions. Based on changes of vesicularity and crystallinity of both subplinian and vulcanian glassy particles, we propose that this change of eruption style was due to varying magma ascent rates in the conduit. The volcanic ash from all eruption styles contained fresh glassy particles, regarded as juvenile materials. The highly-vesiculated particles were classified as P-type (light color) and S-type (dark color), and the poorly-vesiculated particles as WG-type (white), GG-type (gray), and BG-type (dark), with the vesicularity decreasing from P and S particles; WG particles; to GG and BG particles. The crystallinity decreased in the following order: S, GG, and BG particles; then WG particles; and finally P particles. The proportion of highly vesiculated, P and S particles was more than 40 % for the subplinian eruptions, and in the range 7-26 % for the vulcanian eruptions. The preferred orientation of crystals and elongated bubbles in the poorly-vesiculated particles suggest that these particles underwent shear deformation that in turn enhanced outgassing. We combined our crystallinity data with results from other experiments to

  6. Formation of clastogenic lava flows during fissure eruption and scoria cone collapse: the 1986 eruption of Izu-Oshima Volcano, eastern Japan

    NASA Astrophysics Data System (ADS)

    Sumner, Janet M.

    The 1986 eruption of B fissure at Izu-Oshima Volcano, Japan, produced, among other products, one andesite and two basaltic andesite lava flows. Locally the three flows resemble vent-effused holocrystalline blocky or aa lava; however, remnant clast outlines can be identified at most localities, indicating that the flows were spatter fed or clastogenic. The basaltic andesite flows are interpreted to have formed by two main processes: (a) reconstitution of fountain-generated spatter around vent areas by syn-depositional agglutination and coalescence, followed by extensional non-particulate flow, and (b) syn-eruptive collapse of a rapidly built spatter and scoria cone by rotational slip and extensional sliding. These processes produced two morphologically distinct lobes in both flows by: (a) earlier non-particulate flow of agglutinate and coalesced spatter, which formed a thin lobe of rubbly aa lava (ca. 5 m thick) with characteristic open extension cracks revealing a homogeneous, holocrystalline interior, and (b) later scoria-cone collapse, which created a larger lobe of irregular thickness (<20 m) made of large detached blocks of scoria cone interpreted to have been rafted along on a flow of coalesced spatter. The source regions of these lava flows are characterized by horseshoe-shaped scarps (<30 m high), with meso-blocks (ca. 30 m in diameter) of bedded scoria at the base. One lava flow has a secondary lateral collapse zone with lower (ca. 7 m) scarps. Backward-tilted meso-blocks are interpreted to be the product of rotational slip, and forward-tilted blocks the result of simple toppling. Squeeze-ups of coalesced spatter along the leading edge of the meso-blocks indicate that coalescence occurred in the basal part of the scoria cone. This low-viscosity, coalesced spatter acted as a lubricating layer along which basal failure of the scoria cone occurred. Rotational sliding gave way to extensional translational sliding as the slide mass spread out onto the present

  7. Further investigations of automated surface observing system (ASOS) winds used in air quality modeling applications

    SciTech Connect

    Brower, R.P.; Jones, W.B.; Sherwell, J.

    1999-07-01

    Since 1992, a significant shift in the way standard surface meteorological data are observed and collected has occurred across the country. The National Weather Service, the Federal Aviation Administration, and the Department of Defense have been deploying the Automated Surface Observing System (ASOS) at nearly one thousand sites. Prior to ASOS, manual observation and recordation were the norm. With the advent of ASOS, an unprecedented level of meteorological data is now available; observations of standard meteorological variables are available almost real-time at more sites. However, with ASOS, meteorological data are being gathered in a fundamentally different way. New automated instruments sample, analyze, and record meteorological observations without human intervention. Many of these meteorological observations are key inputs to predictive air quality models. Reliable estimates of plume transport and dispersion require reliable and available meteorological data. The effect of the ASOS method of data collection on the dispersion modeling community is not clear. Because the hourly data now being reported at most stations across the country are being gathered in a fundamentally different way than previously, it is prudent to examine the differences between hourly meteorological observations gathered before and after ASOS. A preliminary analysis1 of pre-ASOS and ASOS data suggested that the differences in the observations could impact the data's application to air quality models. This expanded study examines more thoroughly the differences between wind data gathered before and after ASOS implementation in order to identify potential ramifications for air quality modeling. Pre-ASOS and ASOS data, from five stations in and around Maryland that represent the diversity of urbanization and topography of the region and that have a reasonably long record of ASOS observations, are examined.

  8. Spatial heterogeneities in tectonic stress in Kyushu, Japan and their relation to a major shear zone

    NASA Astrophysics Data System (ADS)

    Matsumoto, Satoshi; Nakao, Shigeru; Ohkura, Takahiro; Miyazaki, Masahiro; Shimizu, Hiroshi; Abe, Yuki; Inoue, Hiroyuki; Nakamoto, Manami; Yoshikawa, Shin; Yamashita, Yusuke

    2015-10-01

    We investigated the spatial variation in the stress fields of Kyushu Island, southwestern Japan. Kyushu Island is characterized by active volcanoes (Aso, Unzen, Kirishima, and Sakurajima) and a shear zone (western extension of the median tectonic line). Shallow earthquakes frequently occur not only along active faults but also in the central region of the island, which is characterized by active volcanoes. We evaluated the focal mechanisms of the shallow earthquakes on Kyushu Island to determine the relative deviatoric stress field. Generally, the stress field was estimated by using the method proposed by Hardebeck and Michael (2006) for the strike-slip regime in this area. The minimum principal compression stress ( σ3), with its near north-south trend, is dominant throughout the entire region. However, the σ 3 axes around the shear zone are rotated normal to the zone. This result is indicative of shear stress reduction at the zone and is consistent with the right-lateral fault behavior along the zone detected by a strain-rate field analysis with global positioning system data. Conversely, the stress field of the normal fault is dominant in the Beppu-Shimabara area, which is located in the central part of the island. This result and the direction of σ3 are consistent with the formation of a graben structure in the area.

  9. Estimation of regional resistivity structure beneath the Kyushu, southwestern Japan, as inferred from the Network-MT survey

    NASA Astrophysics Data System (ADS)

    Hata, M.; Oshiman, N.; Yoshimura, R.; Tanaka, Y.; Uyeshima, M.; Ichiki, M.

    2008-12-01

    Network-MT observations, which use telephone line networks as long baseline telluric measurements (Uyeshima, 1990), were carried out in the Kyushu district, southwestern Japan, from 1993 to 1998. The Kyushu district is the typical high angle subduction zone in Japan, which the Philippine sea plate subducts beneath the Eurasian plate, and some active volcanoes (for example, the Aso volcano, the Kirishima volcano group and Sakurajima volcano) are located along the volcanic front. We reanalyzed these data sets to determine regional scale deep electrical conductivity structure. In this reanalysis, we tried to choose triangular elements of the Network-MT again in order to obtain independency of each triangular element, and calculated magnetotelluric responses for each triangular element showing more suitable spatial distribution in survey area. Furthermore, comparing the geology and tectonics, we estimated electrical tendency to by the phase tensors analysis (Caldwell et al., 2004). As a preparatory step for imaging three-dimensional modeling, we carried out several tow dimensional inversion analyses to the Network-MT impedance responses across the characteristic geology, tectonics and volcanoes. In these two-dimensional inversions, we used the REBOCC code (Siripunvaraporn and Egbert, 1999), and reconsidered the horizontal and vertical smoothing factors while considering the intervals of the observation sites along each model profile. Then we obtained the final resistivity model of each profile which was judged expressing well the information of the MT responses. As a preliminary result, one of the resistivity models, whose profile goes along around the Kirishima volcano group, we obtained a remarkable conductor beneath the Kirishima volcano which shows a good agreement with the previous result of ULF MT survey (Ichiki et al., 2000). Further, we found that the bottom of this conductor extends to the subducting Philippine Sea Plate. However, at the present stage, we

  10. Geomorphology and sedimentary features, and temporal component-change of lahar deposits at the northern foot of Chokai volcano, NE Japan

    NASA Astrophysics Data System (ADS)

    Minami, Y.; Ohba, T.; Kataoka, K.; Hayashi, S.

    2014-12-01

    Chokai volcano is an andesitic stratovolcano that collapsed to the north ca.2500 years ago. The post-collapse fan deposits are distributed in the northern foot of the volcano, and to reveal their depositional process in terms of modern sedimentology, we carried out the geological study includung digging survey, as well as geomorphological analysis, mineralogy, and 14C chronology. Consequently, the geological study revealed that the fan deposits consist of more than 16 units, which are debris flow, hyperconcentrated flow and streamflow deposits. We give hare general name lahar deposits for these deposits. The lahar deposits have a total thickness of 30 m, and overlie the 2.5-ka Kisakata debris avalanche deposit. The lahar deposits form a part of volcanic fan and volcaniclastic apron of Chokai volcano. In proximal areas (steep or moderate sloped areas), the lahar flowed down as debris flows, and in the distal area (horizontal area) the lahars transformed into hyperconcentrated flow or stream flows but partly arrived the area as debris flow. The hyperconcentrated flows or stream flows reached the horizontal area at least four times, supposed by AMS dating (the ages of some lahar deposits are 2200, 1500-1600, 1000-1200, and 100-200 yBP). The lahar deposits contain clasts of altered andesite, fresh andesite, mudstone and sandstone. Proportions of altered andesite clasts to total clasts decrease upwards in stratigraphic sequence. Matrices of the lower eight units are composed of grayish-blue clay, and are different from those of the upper eight units, composed of brownish yellow volcanic sand. The stratigraphic variation in matrix component is consistent with the change in matrix mineral assemblage, possibly reflecting changes in the source materials from Chokai volcano.

  11. Geological and petrological evidences for mingling and mixing of magmas in the Me-akan and Taisetsu volcanoes, eastern and central Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Wada, Keiji; Sato, Eiichi; Anzai, Keisuke; Baba, Hikaru

    2015-04-01

    Both the Me-akan volcano, eastern Hokkaido, and the Taisetsu volcano, central Hokkaido, are exactly the clear fields showing geological evidences for magma mingling and magma mixing, such as coexistence of basaltic andesite scoria and dacite pumice in plinian fall deposit, heterogeneous juvenile ejecta (banded pumice, etc.) in pyroclastic flow, mafic inclusions in lavas, and banded structure in lavas. Throughout the eruption history of Me-Akan volcano, the largest eruptions occurred about 12000-13000 years ago. The main eruptions of this stage were continuously eruptive sequence of pumice-scoria pyroclastic flows and pumice-scoria plinian fallout, which show the multi-stage processes of magma mixing and mingling in the magma plumbing system through mineralogical and petrological analyses of the juvenile products. Each deposit contains pumice (SiO2=63wt.%), scoria (SiO2=55wt.%) and heterogeneous scoria. The core composition of plagioclase phenocrysts of these scoria and pumice shows a same bimodal distribution of low-An plagioclase (An=59) and high-An plagioclase (An>70). These indicate that heterogeneous ejecta such as banded pumice were exactly mingling products of both mixed mafic and felsic magmas, which were derived from continuous magma mixing of felsic and mafic end-member magmas in a zoned magma chamber. The lavas in Taisetsu volcano frequently show the banded structure of andesite and dacite magmas, and are characterized by containing a number of mafic inclusions with coarse- and fine-grained types. These inclusions were originated from two kinds of mafic end-member magmas and have different resident times in magma chamber. Some coarse-type inclusion was probably brought out from dacite crystal mush layer. The plagioclase phenocrysts in the host lava show trimodal An-content distributions (

  12. Chikurachki Volcano

    Atmospheric Science Data Center

    2013-04-16

    ... plume from the April 22, 2003, eruption of the Chikurachki volcano is portrayed in these views from the Multi-angle Imaging ... the volcanically active Kuril Island group, the Chikurachki volcano is an active stratovolcano on Russia's Paramushir Island (just south of ...

  13. Dante's volcano

    NASA Astrophysics Data System (ADS)

    1994-09-01

    This video contains two segments: one a 0:01:50 spot and the other a 0:08:21 feature. Dante 2, an eight-legged walking machine, is shown during field trials as it explores the inner depths of an active volcano at Mount Spurr, Alaska. A NASA sponsored team at Carnegie Mellon University built Dante to withstand earth's harshest conditions, to deliver a science payload to the interior of a volcano, and to report on its journey to the floor of a volcano. Remotely controlled from 80-miles away, the robot explored the inner depths of the volcano and information from onboard video cameras and sensors was relayed via satellite to scientists in Anchorage. There, using a computer generated image, controllers tracked the robot's movement. Ultimately the robot team hopes to apply the technology to future planetary missions.

  14. Dante's Volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This video contains two segments: one a 0:01:50 spot and the other a 0:08:21 feature. Dante 2, an eight-legged walking machine, is shown during field trials as it explores the inner depths of an active volcano at Mount Spurr, Alaska. A NASA sponsored team at Carnegie Mellon University built Dante to withstand earth's harshest conditions, to deliver a science payload to the interior of a volcano, and to report on its journey to the floor of a volcano. Remotely controlled from 80-miles away, the robot explored the inner depths of the volcano and information from onboard video cameras and sensors was relayed via satellite to scientists in Anchorage. There, using a computer generated image, controllers tracked the robot's movement. Ultimately the robot team hopes to apply the technology to future planetary missions.

  15. Formation of a zoned magma chamber and its temporal evolution during the historic eruptive activity of Tarumai Volcano, Japan: Petrological implications for a long-term forecast of eruptive activity of an active volcano

    NASA Astrophysics Data System (ADS)

    Nakagawa, Mitsuhiro; Hiraga, Naoto; Furukawa, Ryuta

    2011-08-01

    Tarumai Volcano started a series of historic eruptive activity in AD 1667 after a dormancy of approximately 2000 years. The historic juvenile ejecta are mainly silicic andesite pumice associated with scoria, banded pumice and dome lava (SiO 2 = 55-63%), and are mixing products of two or three end-member magmas. In the initial largest plinian eruptions (AD 1667 period), simple mixing between two end-member magmas, silicic andesite (SA) and basalt, occurred. Large plinian eruptions (AD 1739 period) and the latest intermittent eruptions (AD 1804-AD 1909: latest period) also produced mixed magmas including both the SA, intermediate-SiO 2 andesite (IA), and basalt. Magmatic temperatures of the SA and IA magmas are 900-950 °C and approximately 1000 °C, respectively. The rocks of each period form linear trends in oxide-oxide diagrams, suggesting that mixing of two end-member magmas occurred in each period. Thus, it can be estimated that the IA magma was formed by mixing between the basaltic and SA magmas. These relations suggest that the injection of the basaltic magma into the SA magma occurred before the AD 1667 period, resulting in the formation of a zoned magma chamber. These two magmas were then withdrawn to mingle, during the AD 1667 period. After the period, the zoned chamber was composed of an upper SA magma and a lower mixed IA magma. Chemical compositions of the basaltic magma have been slightly different in each period since AD 1667. In addition, the phenocrystic minerals of the IA magma also have changed as a consequence of re-equilibration with the more mafic IA bulk magma compositions present from AD 1739 to AD 1909. Thus, distinct basaltic magma has repeatedly injected into the zoned chamber before each eruption. Although the scale of eruptions became much smaller after the plinian eruptions of AD 1739, the ratio of IA magma in the latest eruptive materials is much larger than that in AD 1739, suggesting that a larger amount of the lower part (IA magma

  16. AgNa2Mo3O9AsO4

    PubMed Central

    Hamza, Hamadi; Zid, Mohamed Faouzi; Driss, Ahmed

    2011-01-01

    The title compound, silver disodium trimolybdenum(VI) nonaoxide arsenate, AgNa2Mo3O9AsO4, was prepared by a solid-state reaction at 808 K. The structure consists of an infinite (Mo3AsO13)n ribbon, parallel to the c axis, composed of AsO4 tetra­hedra and MoO6 octa­hedra sharing edges and corners. The Na and Ag ions partially occupy several independent close positions, with various occupancies, in the inter-ribbon space delimited by the one-dimensional framework. The composition was refined to Ag1.06(1)Na1.94(1)Mo3O9AsO4. PMID:22219728

  17. Mineralogical study on volcanic ash of the eruption on September 27, 2014 at Ontake volcano, central Japan: correlation with porphyry copper systems

    NASA Astrophysics Data System (ADS)

    Minami, Yusuke; Imura, Takumi; Hayashi, Shintaro; Ohba, Tsukasa

    2016-04-01

    The volcanic ash of the eruption on September 27, 2014 at Ontake volcano consists mostly of altered rock fragments. The ash contains partly altered volcanic rock fragments consisting of primary igneous minerals (plagioclase, orthopyroxene, titanomagnetite, and feldspars) and volcanic glass accompanied by alteration minerals to some extents, and contains no juvenile fragments. These features indicate that the eruption was a non-juvenile hydrothermal eruption that was derived from the hydrothermal system developed under the crater. The major minerals derived from hydrothermal alteration zones are silica mineral, kaolin-group mineral, smectite, pyrophyllite, muscovite, alunite, anhydrite, gypsum, pyrite, K-feldspar, albite, and rutile. Minor chlorite, biotite, and garnet are accompanied. Five types of alteration mineral associations are identified from observations on individual ash particles: silica-pyrite, silica-pyrite ± alunite ± kaolin, silica-pyrophyllite-pyrite, silica-muscovite ± chlorite, and silica-K-feldspar ± albite ± garnet ± biotite. The associations indicate development of advanced argillic, sericite, and potassic alteration zones under the crater. Occurrence of anhydrite veinlet and the set of alteration zones indicate hydrothermal alteration zones similar to late-stage porphyry copper systems. Comparing the mineral associations with the geologic model of the late-stage porphyry copper systems, the source depths of mineral associations are estimated to range from near surface to >2 km. The depths of advanced argillic alteration, sericite, and potassic zones are 0 to ~2, ~1.5 to ~2, and >2 km, respectively.

  18. Temporal evolution of a hydrothermal system in Kusatsu-Shirane Volcano, Japan, inferred from the complex frequencies of long-period events

    USGS Publications Warehouse

    Kumagai, H.; Chouet, B.A.; Nakano, M.

    2002-01-01

    We present a detailed description of temporal variations in the complex frequencies of long-period (LP) events observed at Kusatsu-Shirane Volcano. Using the Sompi method, we analyze 35 LP events that occurred during the period from August 1992 through January 1993. The observed temporal variations in the complex frequencies can be divided into three periods. During the first period the dominant frequency rapidly decreases from 5 to 1 Hz, and Q of the dominant spectral peak remains roughly constant with an average value near 100. During the second period the dominant frequency gradually increases up to 3 Hz, and Q gradually decreases from 160 to 30. During the third period the dominant frequency increases more rapidly from 3 to 5 Hz, and Q shows an abrupt increase at the beginning of this period and then remains roughly constant with an average value near 100. Such temporal variations can be consistently explained by the dynamic response of a hydrothermal crack to a magmatic heat pulse. During the first period, crack growth occurs in response to the overall pressure increase in the hydrothermal system caused by the heat pulse. Once crack formation is complete, heat gradually changes the fluid in the crack from a wet misty gas to a dry gas during the second period. As heating of the hydrothermal system gradually subsides, the overall pressure in this system starts to decrease, causing the collapse of the crack during the third period.

  19. Spreading Volcanoes

    NASA Astrophysics Data System (ADS)

    Borgia, Andrea; Delaney, Paul T.; Denlinger, Roger P.

    As volcanoes grow, they become ever heavier. Unlike mountains exhumed by erosion of rocks that generally were lithified at depth, volcanoes typically are built of poorly consolidated rocks that may be further weakened by hydrothermal alteration. The substrates upon which volcanoes rest, moreover, are often sediments lithified by no more than the weight of the volcanic overburden. It is not surprising, therefore, that volcanic deformation includes-and in the long term is often dominated by-spreading motions that translate subsidence near volcanic summits to outward horizontal displacements around the flanks and peripheries. We review examples of volcanic spreading and go on to derive approximate expressions for the time volcanoes require to deform by spreading on weak substrates. We also demonstrate that shear stresses that drive low-angle thrust faulting from beneath volcanic constructs have maxima at volcanic peripheries, just where such faults are seen to emerge. Finally, we establish a theoretical basis for experimentally derived scalings that delineate volcanoes that spread from those that do not.

  20. Spreading volcanoes

    USGS Publications Warehouse

    Borgia, A.; Delaney, P.T.; Denlinger, R.P.

    2000-01-01

    As volcanoes grow, they become ever heavier. Unlike mountains exhumed by erosion of rocks that generally were lithified at depth, volcanoes typically are built of poorly consolidated rocks that may be further weakened by hydrothermal alteration. The substrates upon which volcanoes rest, moreover, are often sediments lithified by no more than the weight of the volcanic overburden. It is not surprising, therefore, that volcanic deformation includes-and in the long term is often dominated by-spreading motions that translate subsidence near volcanic summits to outward horizontal displacements around the flanks and peripheries. We review examples of volcanic spreading and go on to derive approximate expressions for the time volcanoes require to deform by spreading on weak substrates. We also demonstrate that shear stresses that drive low-angle thrust faulting from beneath volcanic constructs have maxima at volcanic peripheries, just where such faults are seen to emerge. Finally, we establish a theoretical basis for experimentally derived scalings that delineate volcanoes that spread from those that do not.

  1. Detection of microwave emission due to rock fracture as a new tool for geophysics: A field test at a volcano in Miyake Island, Japan

    NASA Astrophysics Data System (ADS)

    Takano, Tadashi; Maeda, Takashi; Miki, Yoji; Akatsuka, Sayo; Hattori, Katsumi; Nishihashi, Masahide; Kaida, Daishi; Hirano, Takuya

    2013-07-01

    This paper describes a field test to verify a newly discovered phenomenon of microwave emission due to rock fracture in a volcano. The field test was carried out on Miyake Island, 150 km south of Tokyo. The main objective of the test was to investigate the applicability of the phenomenon to the study of geophysics, volcanology, and seismology by extending observations of this phenomenological occurrence from the laboratory to the natural field. We installed measuring systems for 300 MHz, 2 GHz, and 18 GHz-bands on the mountain top and mountain foot in order to discriminate local events from regional and global events. The systems include deliberate data subsystems that store slowly sampled data in the long term, and fast sampled data when triggered. We successfully obtained data from January to February 2008. During this period, characteristic microwave pulses were intermittently detected at 300 MHz. Two photographs taken before and after this period revealed that a considerably large-scale collapse occurred on the crater cliff. Moreover, seismograms obtained by nearby observatories strongly suggest that the crater subsidence occurred simultaneously with microwave signals on the same day during the observation period. For confirmation of the microwave emission caused by rock fracture, these microwave signals must be clearly discriminated from noise, interferences, and other disturbances. We carefully discriminated the microwave data taken at the mountaintop and foot, checked the lightning strike data around the island, and consequently concluded that these microwave signals could not be attributed to lightning. Artificial interferences were discriminated by the nature of their waveforms. Thus, we inferred that the signals detected at 300 MHz were due to rock fractures during cliff collapses. This result may provide a useful new tool for geoscientists and for the mitigation of natural hazards.

  2. Chilean Volcanoes

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On the border between Chile and the Catamarca province of Argentina lies a vast field of currently dormant volcanoes. Over time, these volcanoes have laid down a crust of magma roughly 2 miles (3.5 km) thick. It is tinged with a patina of various colors that can indicate both the age and mineral content of the original lava flows. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on May 15, 1999. This is a false-color composite image made using shortwave infrared, infrared, and green wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  3. Effect of syneruptive decompression path on shifting intensity in basaltic sub-Plinian eruption: Implication of microlites in Yufune-2 scoria from Fuji volcano, Japan

    NASA Astrophysics Data System (ADS)

    Suzuki, Yuki; Fujii, Toshitsugu

    2010-12-01

    To constrain the timing and conditions of syneruptive magma ascent that are responsible for shifting eruption intensity, we have investigated a basaltic sub-Plinian eruption that produced Yufune-2 scoria in Fuji volcano 2200 years ago. We deduced magmatic decompression conditions from groundmass microlite textures, including decompression path (i.e. evolution in decompression rate) and approximate decompression rate, in order to relate them to eruption intensity. The microlites revealed decompression conditions after water saturation at 700-1100 m depth. The temporal change in scoria size indicates that the magma discharge rate and resultant eruption intensity increased from unit a to unit b, and then declined toward ending units d and e. The overall decompression rate in each eruptive unit has a positive correlation with eruption intensity. The variation in decompression rate was enlarged in the final units, where the maximum remained the same as the peak through the eruption (0.13-0.22 MPa/s for units b and c), while the minimum was 0.025 MPa/s. The large variation here is due to 1) variation in flow velocity across conduit and 2) part of the erupted magma in unit d experienced remarkably slow decompression (0.002-0.003 MPa/s) resulting from decreased overpressure in the reservoir following the major eruption of unit b. Furthermore, crystal size distribution (CSD) of microlites implied that the earliest erupted magma (unit a) had once been decompressed slowly (0.005-0.012 MPa/s), having been arrested by material in the conduit-vent system, which was followed by an increase in decompression rate due to removal of the material at the initiation of the eruption. In addition, the magma that had been ascending slowly before the unit-d eruption may record the increase in decompression rate. This increased rate resulted from being pushed up by the successive magma at the start of that eruption. Two factors had a major impact on eruption intensity. First, magma

  4. Iceland Volcano

    Atmospheric Science Data Center

    2013-04-23

    ... of which are so thick that they block the penetration of light from CALIPSO's lidar to the surface. The yellow layer near the surface over France is believed to be primarily air pollution, but could also contain ash from the volcano. Highlighting its ...

  5. Santorini Volcano

    USGS Publications Warehouse

    Druitt, T.H.; Edwards, L.; Mellors, R.M.; Pyle, D.M.; Sparks, R.S.J.; Lanphere, M.; Davies, M.; Barreirio, B.

    1999-01-01

    Santorini is one of the most spectacular caldera volcanoes in the world. It has been the focus of significant scientific and scholastic interest because of the great Bronze Age explosive eruption that buried the Minoan town of Akrotiri. Santorini is still active. It has been dormant since 1950, but there have been several substantial historic eruptions. Because of this potential risk to life, both for the indigenous population and for the large number of tourists who visit it, Santorini has been designated one of five European Laboratory Volcanoes by the European Commission. Santorini has long fascinated geologists, with some important early work on volcanoes being conducted there. Since 1980, research groups at Cambridge University, and later at the University of Bristol and Blaise Pascal University in Clermont-Ferrand, have collected a large amount of data on the stratigraphy, geochemistry, geochronology and petrology of the volcanics. The volcanic field has been remapped at a scale of 1:10 000. A remarkable picture of cyclic volcanic activity and magmatic evolution has emerged from this work. Much of this work has remained unpublished until now. This Memoir synthesizes for the first time all the data from the Cambridge/Bristol/Clermont groups, and integrates published data from other research groups. It provides the latest interpretation of the tectonic and magmatic evolution of Santorini. It is accompanied by the new 1:10 000 full-colour geological map of the island.

  6. Development of antisense oligonucleotide (ASO) technology against Tgf-β signaling to prevent scarring during flexor tendon repair.

    PubMed

    Loiselle, Alayna E; Yukata, Kiminori; Geary, Michael B; Kondabolu, Sirish; Shi, Shanshan; Jonason, Jennifer H; Awad, Hani A; O'Keefe, Regis J

    2015-06-01

    Flexor tendons (FT) in the hand provide near frictionless gliding to facilitate hand function. Upon injury and surgical repair, satisfactory healing is hampered by fibrous adhesions between the tendon and synovial sheath. In the present study we used antisense oligonucleotides (ASOs), specifically targeted to components of Tgf-β signaling, including Tgf-β1, Smad3 and Ctgf, to test the hypothesis that local delivery of ASOs and suppression of Tgf-β1 signaling would enhance murine FT healing by suppressing adhesion formation while maintaining strength. ASOs were injected in to the FT repair site at 2, 6 and 12 days post-surgery. ASO treatment suppressed target gene expression through 21 days. Treatment with Tgf-β1, Smad3 or Ctgf ASOs resulted in significant improvement in tendon gliding function at 14 and 21 days, relative to control. Consistent with a decrease in adhesions, Col3a1 expression was significantly decreased in Tgf-β1, Smad3 and Ctgf ASO treated tendons relative to control. Smad3 ASO treatment enhanced the maximum load at failure of healing tendons at 14 days, relative to control. Taken together, these data support the use of ASO treatment to improve FT repair, and suggest that modulation of the Tgf-β1 signaling pathway can reduce adhesions while maintaining the strength of the repair. PMID:25761254

  7. Development of Antisense Oligonucleotide (ASO) Technology Against Tgf-β Signaling to Prevent Scarring During Flexor Tendon Repair

    PubMed Central

    Loiselle, Alayna E.; Yukata, Kiminori; Geary, Michael B.; Kondabolu, Sirish; Shi, Shanshan; Jonason, Jennifer H.; Awad, Hani A.; O’Keefe, Regis J.

    2015-01-01

    Flexor tendons (FT) in the hand provide near frictionless gliding to facilitate hand function. Upon injury and surgical repair, satisfactory healing is hampered by fibrous adhesions between the tendon and synovial sheath. In the present study we used antisense oligonucleotides (ASOs), specifically targeted to components of Tgf-β signaling, including Tgf-β1, Smad3 and Ctgf, to test the hypothesis that local delivery of ASOs and suppression of Tgf-β1 signaling would enhance murine FT healing by suppressing adhesion formation while maintaining strength. ASOs were injected in to the FT repair site at 2, 6 and 12 days post-surgery. ASO treatment suppressed target gene expression through 21 days. Treatment with Tgf-β1, Smad3 or Ctgf ASOs resulted in significant improvement in tendon gliding function at 14 and 21 days, relative to control. Consistent with a decrease in adhesions, Col3a1 expression was significantly decreased in Tgf-β1, Smad3 and Ctgf ASO treated tendons relative to control. Smad3 ASO treatment enhanced the max load at failure of healing tendons at 14 days, relative to control. Taken together, these data support the use of ASO treatment to improve FT repair, and suggest that modulation of the Tgf-β1 signaling pathway can reduce adhesions while maintaining the strength of the repair. PMID:25761254

  8. 78 FR 18314 - Foreign-Trade Zone 169-Manatee County, Florida; Application for Production Authority; ASO, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Foreign-Trade Zones Board Foreign-Trade Zone 169--Manatee County, Florida; Application for Production Authority; ASO, LLC; Subzone 169A (Textile Fabric Adhesive Bandage Coating and Production); Sarasota... facility is used for the production of plastic and textile fabric adhesive bandages. ASO is also...

  9. Soufriere Hills Volcano

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this ASTER image of Soufriere Hills Volcano on Montserrat in the Caribbean, continued eruptive activity is evident by the extensive smoke and ash plume streaming towards the west-southwest. Significant eruptive activity began in 1995, forcing the authorities to evacuate more than 7,000 of the island's original population of 11,000. The primary risk now is to the northern part of the island and to the airport. Small rockfalls and pyroclastic flows (ash, rock and hot gases) are common at this time due to continued growth of the dome at the volcano's summit.

    This image was acquired on October 29, 2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is

  10. SAR4Volcanoes: an international ASI funded research project on volcano deformation through new generation SAR sensors

    NASA Astrophysics Data System (ADS)

    Sansosti, E.; Pepe, S.; Solaro, G.; Casu, F.; Tizzani, P.; Acocella, V.; Ruch, J.; Nobile, A.; Puglisi, G.; Guglielmino, F.; Zoffoli, S.

    2012-04-01

    Volcano deformation monitoring is crucial to understand how magma emplaces, propagates and erupts. Therefore, volcano deformation research projects are particularly important opportunities to improve our understanding of volcano dynamics. SAR4Volcanoes is a 2-year research project funded by the Italian Space Agency (ASI) within the framework of a cooperation agreement with the Japan Aerospace Exploration Agency (JAXA). It focuses on volcano deformation analysis through Differential SAR Interferometry (DInSAR) techniques by means of COSMO-SkyMed and ALOS data, through the joint use of L-band and X-band SAR data. It also aims to the identification of methods and techniques to support decision making in emergency cases. Main target volcanoes in the projects are Etna, Vesuvio, Campi Flegrei and Stromboli (Italy) and Sakurajima and Kirishima (Japan). Secondary target volcanoes include recently or currently erupting volcanoes, as El Hierro (Spain), Nabro (Ethiopia) and Galapagos volcanoes (Ecuador). Since the project kickoff (July 2011) a large number of COSMO-SkyMed data has been acquired at these volcanoes; in some cases, the acquisitions are available almost at every satellite orbit, with an average interval down to 4 days. On these premises, the project represents an important opportunity to: (1) collect a significant amount of X-band data on active and erupting volcanoes and (2) study surface deformation to understand magma dynamics in different volcanic settings. We will present preliminary results on the ground deformation analysis of the main and secondary target volcanoes. In particular, target volcanoes without a pre-project archive are analyzed using single deformation maps, while those with archives are analysed through a time series approach, based on the SBAS technique.

  11. K(MoO2)4O3(AsO4)

    PubMed Central

    Jouini, Raja; Zid, Mohamed Faouzi; Driss, Ahmed

    2013-01-01

    A new compound with a non-centrosymmetric structure, potassium tetra­kis­[dioxomolybdenum(IV)] arsenate trioxide, K(MoO2)4O3(AsO4), has been synthesized by a solid-state reaction. The [(MoO2)4O3(AsO4)]+ three-dimensional framework consists of single arsenate AsO4 tetra­hedra, MoO6 octa­hedra, MoO5 bipyramids and bi­octa­hedral units of edge-sharing Mo2O10 octa­hedra. The [Mo2O8]∞ octa­hedral chains running along the a-axis direction are connected through their corners to the AsO4 tetra­hedra, MoO6 octa­hedra and MoO5 bipyramids, so as to form large tunnels propagating along the a axis in which the K+ cations are located. This structure is compared with compounds containing M 2O10 (M = Mo, V, Fe) dimers and with those containing M 2O8 (M = V) chains. PMID:23794968

  12. Mud Volcanoes Formation And Occurrence

    NASA Astrophysics Data System (ADS)

    Guliyev, I. S.

    2007-12-01

    Mud volcanoes are natural phenomena, which occur throughout the globe. They are found at a greater or lesser scale in Azerbaijan, Turkmenistan, Georgia, on the Kerch and Taman peninsulas, on Sakhalin Island, in West Kuban, Italy, Romania, Iran, Pakistan, India, Burma, China, Japan, Indonesia, Malaysia, New Zealand, Mexico, Colombia, Trinidad and Tobago, Venezuela and Ecuador. Mud volcanoes are most well-developed in Eastern Azerbaijan, where more than 30% of all the volcanoes in the world are concentrated. More than 300 mud volcanoes have already been recognized here onshore or offshore, 220 of which lie within an area of 16,000 km2. Many of these mud volcanoes are particularly large (up to 400 m high). The volcanoes of the South Caspian form permanent or temporary islands, and numerous submarine banks. Many hypotheses have been developed regarding the origin of mud volcanoes. Some of those hypotheses will be examined in the present paper. Model of spontaneous excitation-decompaction (proposed by Ivanov and Guliev, 1988, 2002). It is supposed that one of major factors of the movement of sedimentary masses and formation of hydrocarbon deposits are phase transitions in sedimentary basin. At phase transitions there are abnormal changes of physical and chemical parameters of rocks. Abnormal (high and negative) pressure takes place. This process is called as excitation of the underground environment with periodicity from several tens to several hundreds, or thousand years. The relationship between mud volcanism and the generation of hydrocarbons, particularly methane, is considered to be a critical factor in mud volcano formation. At high flow rates the gas and sediment develops into a pseudo-liquid state and as flow increases the mass reaches the "so-called hover velocity" where mass transport begins. The mass of fluid moves as a quasi-uniform viscous mass through the sediment pile in a piston like manner until expelled from the surface as a "catastrophic eruption

  13. Northern Arizona Volcanoes

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Northern Arizona is best known for the Grand Canyon. Less widely known are the hundreds of geologically young volcanoes, at least one of which buried the homes of local residents. San Francisco Mtn., a truncated stratovolcano at 3887 meters, was once a much taller structure (about 4900 meters) before it exploded some 400,000 years ago a la Mt. St. Helens. The young cinder cone field to its east includes Sunset Crater, that erupted in 1064 and buried Native American homes. This ASTER perspective was created by draping ASTER image data over topographic data from the U.S. Geological Survey National Elevation Data.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 20.4 by 24.6 kilometers (12.6 by 15.2 miles) Location: 35.3 degrees North latitude, 111

  14. Cladistic analysis applied to the classification of volcanoes

    NASA Astrophysics Data System (ADS)

    Hone, D. W. E.; Mahony, S. H.; Sparks, R. S. J.; Martin, K. T.

    2007-11-01

    Cladistics is a systematic method of classification that groups entities on the basis of sharing similar characteristics in the most parsimonious manner. Here cladistics is applied to the classification of volcanoes using a dataset of 59 Quaternary volcanoes and 129 volcanic edifices of the Tohoku region, Northeast Japan. Volcano and edifice characteristics recorded in the database include attributes of volcano size, chemical composition, dominant eruptive products, volcano morphology, dominant landforms, volcano age and eruptive history. Without characteristics related to time the volcanic edifices divide into two groups, with characters related to volcano size, dominant composition and edifice morphology being the most diagnostic. Analysis including time based characteristics yields four groups with a good correlation between these groups and the two groups from the analysis without time for 108 out of 129 volcanic edifices. Thus when characters are slightly changed the volcanoes still form similar groupings. Analysis of the volcanoes both with and without time yields three groups based on compositional, eruptive products and morphological characters. Spatial clusters of volcanic centres have been recognised in the Tohoku region by Tamura et al. ( Earth Planet Sci Lett 197:105 106, 2002). The groups identified by cladistic analysis are distributed unevenly between the clusters, indicating a tendency for individual clusters to form similar kinds of volcanoes with distinctive but coherent styles of volcanism. Uneven distribution of volcano types between clusters can be explained by variations in dominant magma compositions through time, which are reflected in eruption products and volcanic landforms. Cladistic analysis can be a useful tool for elucidating dynamic igneous processes that could be applied to other regions and globally. Our exploratory study indicates that cladistics has promise as a method for classifying volcanoes and potentially elucidating dynamic

  15. NaAg(2)Mo(3)O(9)AsO(4).

    PubMed

    Hamza, Hamadi; Zid, Mohamed Faouzi; Driss, Ahmed

    2010-01-01

    The title compound, sodium disilver arsenatotrimolybdate, Na(0.93 (1))Ag(2.07 (1))Mo(3)AsO(13), was prepared by a solid-state reaction. In the crystal structure, isolated AsO(4) tetra-hedra share corners with groups of three edge-sharing MoO(6) octa-hedra. This arrangement leads to the formation of anionic (1) (∞)[Mo(3)AsO(13)](n) ribbons extending parallel to [100]. The three metal sites show occupational disorder by Ag(I) and Na(I) cations, each with a different Ag:Na ratio. The metal cations are situated in the space between the ribbons and are surrounded by terminal O atoms of the ribbons in the form of distorted MO(7) polyhedra (M = Ag, Na) for distances < 3.0 Å. The title compound shows weak ionic conductivity. Structural relationships between different compounds in the quaternary systems M-Sb-P-O, M-Nb-P-O and M-Mo-As-O (M is Ag or an alkali metal) are also discussed. PMID:21587345

  16. Record completeness for individual volcanoes

    NASA Astrophysics Data System (ADS)

    Bebbington, Mark

    2016-04-01

    There has been considerable recent attention paid to completeness in global and regional (e.g. Japan) eruption data bases. This has taken the form of estimating dates at which the record is complete, either at a global or regional level, at a given VEI or magnitude. This has obvious utility when estimating hazard from very large eruptions, which may have effects 1000s of km from source. However, at a more local level, the question of interest is not so much the global, or the regional, completeness level, but the completeness of the record for an individual volcano. For example, forecast hazard is critically dependent on the size of the eruption, but it is impossible even to statistically describe the size distribution without knowing the completeness of the record. Current methods for eruption catalogue completeness using extreme value statistics rely on large samples for their validity, so a new approach is required for individual volcanoes, which may have only a handful of known eruptions. We will consider one possible such approach based using a Bayesian sequential algorithm assuming that the underlying process is Poissonian and that completeness at a lower VEI implies completeness at all higher VEIs. Results for individual volcanoes are compared with regional figures and, time-permitting, implications for a statistical model of VEI discussed.

  17. Wind Measurement and Archival under the Automated Surface Observing System (ASOS): User Concerns and Opportunity for Improvement.

    NASA Astrophysics Data System (ADS)

    Powell, Mark D.

    1993-04-01

    The National Weather Service, as a part of its modernization effort, is implementing the Automated Surface Observing System (ASOS). Much discussion has occurred about various aspects of ASOS versus the current system of manual and automated observations. Based upon a study of the ASOS specifications and an informal survey of potential ASOS winddata users, defects of the wind sampling and archival strategy chosen for ASOS are discussed in terms of their impact on various user groups. Limitations include: 1) hourly observation average periods that do not conform to international recommendations for wind reporting made by the World Meteorological Organization, 2) no regular archival of high-resolution data-potentially valuable research data are destroyed if not identified within a 12-h period, and 3) no emergency power for operation in severe weather conditions. An alternative sampling and archiving strategy is recommended that benefits a wider cross section of users, without detracting from aviation and forecast service requirements, at a cost of less than 1% of the original ASOS portion of the weather service modernization budget.

  18. Wind measurement and archival under the Automated Surface Observing System (ASOS): User concerns and opportunity for improvement

    SciTech Connect

    Powell, M.D. )

    1993-04-01

    The National Weather Service, as a part of its modernization effort, is implementing the Automated Surface Observing System (ASOS). Much discussion has occurred about various aspects of ASOS versus the current system of manual and automated observations. Based upon a study of the ASOS specifications and an informal survey of potential ASOS wind data users, defects of the wind sampling and archival strategy chosen for ASOS are discussed in terms of their impact on various user groups. Limitations include: (1) hourly observation average periods that do not conform to international recommendations for wind reporting made by the World Meteorological Organization, (2) no regular archival of high-resolution data-potentially valuable research data are destroyed if not identified within a 12-h period, and (3) no emergency power for operation in severe weather conditions. An alternative sampling and archiving strategy is recommended that benefits a wider cross section of users, without detracting from aviation and forecast service requirements, at a cost of less than 1 % of the original ASOS portion of the weather service modernization budget.

  19. Shiveluch Volcano, Kamchatka Peninsula, Russia

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On the night of June 4, 2001, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) captured this thermal image of the erupting Shiveluch volcano. Located on Russia's Kamchatka Peninsula, Shiveluch rises to an altitude of 2,447 meters (8,028 feet). The active lava dome complex is seen as a bright (hot) area on the summit of the volcano. To the southwest, a second hot area is either a debris avalanche or hot ash deposit. Trailing to the west is a 25-kilometer (15-mile) ash plume, seen as a cold 'cloud' streaming from the summit. At least 60 large eruptions have occurred here during the last 10,000 years; the largest historical eruptions were in 1854 and 1964.

    Because Kamchatka is located along the major aircraft routes between North America/Europe and Asia, this area is constantly monitored for potential ash hazards to aircraft. The area is part of the 'Ring of Fire,' a string of volcanoes that encircles the Pacific Ocean.

    The lower image is the same as the upper, except it has been color-coded: red is hot, light greens to dark green are progressively colder, and gray/black are the coldest areas.

    The image is located at 56.7 degrees north latitude, 161.3 degrees east longitude.

    ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

  20. A Scientific Excursion: Volcanoes.

    ERIC Educational Resources Information Center

    Olds, Henry, Jr.

    1983-01-01

    Reviews an educationally valuable and reasonably well-designed simulation of volcanic activity in an imaginary land. VOLCANOES creates an excellent context for learning information about volcanoes and for developing skills and practicing methods needed to study behavior of volcanoes. (Author/JN)

  1. Focus: alien volcanos

    NASA Astrophysics Data System (ADS)

    Carroll, Michael; Lopes, Rosaly

    2007-03-01

    Part 1: Volcanoes on Earth - blowing their top; Part 2: Volcanoes of the inner Solar System - dead or alive: the Moon, Mercury, Mars, Venus; Part 3: Volcanoes of the outer Solar System - fire and ice: Io, Europa, Ganymede and Miranda, Titan, Triton, Enceladus.

  2. Chiliques volcano, Chile

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A January 6, 2002 ASTER nighttime thermal infrared image of Chiliques volcano in Chile shows a hot spot in the summit crater and several others along the upper flanks of the edifice, indicating new volcanic activity. Examination of an earlier nighttime thermal infrared image from May 24,2000 showed no thermal anomaly. Chiliques volcano was previously thought to be dormant. Rising to an elevation of 5778 m, Chiliques is a simple stratovolcano with a 500-m-diameter circular summit crater. This mountain is one of the most important high altitude ceremonial centers of the Incas. It is rarely visited due to its difficult accessibility. Climbing to the summit along Inca trails, numerous ruins are encountered; at the summit there are a series of constructions used for rituals. There is a beautiful lagoon in the crater that is almost always frozen.

    The daytime image was acquired on November 19, 2000 and was created by displaying ASTER bands 1,2 and 3 in blue, green and red. The nighttime image was acquired January 6, 2002, and is a color-coded display of a single thermal infrared band. The hottest areas are white, and colder areas are darker shades of red. Both images cover an area of 7.5 x 7.5 km, and are centered at 23.6 degrees south latitude, 67.6 degrees west longitude.

    Both images cover an area of 7.5 x 7.5 km, and are centered at 23.6 degrees south latitude, 67.6 degrees west longitude.

    These images were acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A

  3. Geothermal resources of Kyushu, southwest Japan with special focus on the Kuju volcanic region

    SciTech Connect

    Ehara, S.

    1995-12-31

    Tectonic and geothermal backgrounds of Kyushu Island, are described to understand the thermal regime of Kuju volcano. A model for the geothermal system beneath Kuju volcano is presented based on thermal, isotopic and structural data. Based on the model, the geothermal resources beneath Kuju volcano are classified into five categories and are estimated by a volume method. The volcano energy stored beneath Kuju volcano is one of very promising potential resources in Japan. It would seem more reasonable to develop technologies to utilize volcano energy step by step.

  4. Volcano seismology

    USGS Publications Warehouse

    Chouet, B.

    2003-01-01

    A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with wide dynamic range, and development of new powerful analysis techniques, rapid progress is being made toward a synthesis of high-quality seismic data to develop a coherent model of eruption mechanics. Examples of recent advances are: (1) high-resolution tomography to image subsurface volcanic structures at scales of a few hundred meters; (2) use of small-aperture seismic antennas to map the spatio-temporal properties of long-period (LP) seismicity; (3) moment tensor inversions of very-long-period (VLP) data to derive the source geometry and mass-transport budget of magmatic fluids; (4) spectral analyses of LP events to determine the acoustic properties of magmatic and associated hydrothermal fluids; and (5) experimental modeling of the source dynamics of volcanic tremor. These promising advances provide new insights into the mechanical properties of volcanic fluids and subvolcanic mass-transport dynamics. As new seismic methods refine our understanding of seismic sources, and geochemical methods better constrain mass balance and magma behavior, we face new challenges in elucidating the physico-chemical processes that cause volcanic unrest and its seismic and gas-discharge manifestations. Much work remains to be done toward a synthesis of seismological, geochemical, and petrological observations into an integrated model of volcanic behavior. Future important goals must include: (1) interpreting the key types of magma movement, degassing and boiling events that produce characteristic seismic phenomena; (2) characterizing multiphase fluids in subvolcanic

  5. ASTER Images Mt. Usu Volcano

    NASA Technical Reports Server (NTRS)

    2000-01-01

    On April 3, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra Satellite captured this image of the erupting Mt. Usu volcano in Hokkaido, Japan. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image the Earth for the next 6 years to map and monitor the changing surface of our planet.

    This false color infrared image of Mt Usu volcano is dominated by Lake Toya, an ancient volcanic caldera. On the south shore is the active Usu volcano. On Friday, March 31, more than 11,000 people were evacuated by helicopter, truck and boat from the foot of Usu, that began erupting from the northwest flank, shooting debris and plumes of smoke streaked with blue lightning thousands of feet in the air. Although no lava gushed from the mountain, rocks and ash continued to fall after the eruption. The region was shaken by thousands of tremors before the eruption. People said they could taste grit from the ash that was spewed as high as 2,700 meters (8,850 ft) into the sky and fell to coat surrounding towns with ash. 'Mount Usu has had seven significant eruptions that we know of, and at no time has it ended quickly with only a small scale eruption,' said Yoshio Katsui, a professor at Hokkaido University. This was the seventh major eruption of Mount Usu in the past 300 years. Fifty people died when the volcano erupted in 1822, its worst known eruption.

    In the image, most of the land is covered by snow. Vegetation, appearing red in the false color composite, can be seen in the agricultural fields, and forests in the mountains. Mt. Usu is crossed by three dark streaks. These are the paths of ash deposits that rained out from eruption plumes two days earlier. The prevailing wind was from the northwest, carrying the ash away from the main city of Date. Ash deposited can be traced on the image as far away as 10 kilometers (16

  6. Alaska Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Murray, Tom; Read, Cyrus

    2008-01-01

    Steam plume from the 2006 eruption of Augustine volcano in Cook Inlet, Alaska. Explosive ash-producing eruptions from Alaska's 40+ historically active volcanoes pose hazards to aviation, including commercial aircraft flying the busy North Pacific routes between North America and Asia. The Alaska Volcano Observatory (AVO) monitors these volcanoes to provide forecasts of eruptive activity. AVO is a joint program of the U.S. Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Augustine volcano and AVO at http://www.avo.alaska.edu.

  7. Geological background and geodynamic mechanism of Mt. Changbai volcanoes on the China-Korea border

    NASA Astrophysics Data System (ADS)

    Liu, Jia-qi; Chen, Shuang-shuang; Guo, Zheng-fu; Guo, Wen-feng; He, Huai-yu; You, Hai-tao; Kim, Hang-min; Sung, Gun-ho; Kim, Haenam

    2015-11-01

    The intense Cenozoic volcanism of Mt. Changbai provides a natural laboratory for investigating the characteristics of volcanism and the dynamical evolution of the Northeast Asian continental margin. Mt. Changbai volcanoes predominantly consist of Wangtian'e volcano in China, Tianchi volcano spanning China and DPR Korea, and Namphothe volcano in DPR Korea. Geochronology data and historical records of volcanism indicate that the three eruption centers were formed in the following sequence: Wangtian'e volcano to Namphothe and Tianchi volcano, advancing temporally and spatially from southwest to northeast. The three eruption centers of Mt. Changbai volcano are located close together, have similar magma evolution trends, bimodal volcanic rock distribution, and an enriched mantle source, etc. Although the Cenozoic volcanism in Mt. Changbai is thought to be somewhat related to the subduction of the Western Pacific Plate, the regularity of volcanic activity and petrography characteristics have continental rift affinity. We therefore conclude that the occurrence of synchronous and similar volcanic activity on both sides of the Japan Sea (i.e., the Japan Arc and Northeast China) likely respond to the rift expansion and the back-arc spreading of Japan Sea. From many perspectives, Mt. Changbai volcano is a giant active volcano with hidden potentially eruptive risks.

  8. Field Management System (FMS) user's manual. Atlanta Support Office Phase I, Version ASO-2

    SciTech Connect

    Not Available

    1985-06-01

    This manual describes the Field Management System (FMS) designed for the Department of Energy Atlanta Support Office (ASO). This manual is written for both the FMS manager and the first-time computer user. The manual is written and FMS is designed so that these users can operate FMS without learning a lot about the computer operations. The chapters of this manual have been arranged so that selected chapters can be combined into separate manuals for the needs of each user. This arrangement is as follows: Data Inspection; Data Entry; FMS Maintenance; and FMS Manager.

  9. Volcanoes: Nature's Caldrons Challenge Geochemists.

    ERIC Educational Resources Information Center

    Zurer, Pamela S.

    1984-01-01

    Reviews various topics and research studies on the geology of volcanoes. Areas examined include volcanoes and weather, plate margins, origins of magma, magma evolution, United States Geological Survey (USGS) volcano hazards program, USGS volcano observatories, volcanic gases, potassium-argon dating activities, and volcano monitoring strategies.…

  10. Distant Mt. Fuji, Island of Honshu Japan

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This distant view of Mt. Fuji, on the main home island of Honshu, Japan (34.0N, 139.0E) was taken from about 450 miles to the south. Evan at that great distance, the majestic and inspiring Mt. Fuji is still plainly visible and easily recognized as a world renowned symbol of Japan. The snow capped extinct volcano lies just a few miles south of Tokyo.

  11. Galactic Super Volcano Similar to Iceland Volcano

    NASA Video Gallery

    This composite image from NASAs Chandra X-ray Observatory with radio data from the Very Large Array shows a cosmic volcano being driven by a black hole in the center of the M87 galaxy. This eruptio...

  12. FOREWORD: The 9th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas (ASOS 9)

    NASA Astrophysics Data System (ADS)

    Wahlgren, Glenn M.; Wiese, Wolfgang L.; Beiersdorfer, Peter

    2008-07-01

    For the first time since its inaugural meeting in Lund in 1983, the triennial international conference on Atomic Spectroscopy and Oscillator Strengths for Astrophysical and Laboratory Plasmas (ASOS) returned to Lund, Sweden. Lund has been a home to atomic spectroscopy since the time of Janne Rydberg, and included the pioneering work in laboratory and solar spectroscopy of Bengt Edlén, who presented the initial ASOS talk in 1983. The ninth ASOS was hosted by the Lund Observatory and the Physics Department of Lund University during from 8 to 10 August 2007 and was attended by nearly 100 registrants. An encouraging sign for the field was the number of young researchers in attendance. This volume contains the submitted contributions from the poster presentations of the conference, and represents approximately forty percent of the presented posters. A complementary volume of Physica Scripta provides the written transactions of the ASOS9 invited presentations. With these two volumes the character of ASOS9 is more fully evident, and they serve as a review of the state of atomic spectroscopy for spectrum analysis and the determination of oscillator strengths and their applications. The goal of ASOS is to be a forum for atomic spectroscopy where both the providers and users of atomic data, which includes wavelengths, energy levels, lifetimes, oscillator strengths, and line shape parameters, can meet to discuss recent advances in experimental and theoretical techniques and their application to understanding the physical processes that are responsible for producing observed spectra. The applications mainly originate from the fields of astrophysics and plasma physics, the latter including fusion energy and lighting research. As a part of ASOS9 we were honored to celebrate the retirement of Professor Sveneric Johansson. At a special session on the spectroscopy of iron, which was conducted in his honor, he presented his insights into the Fe II term system and his most recent

  13. Vibrational spectroscopic study of the mineral pitticite Fe, AsO 4, SO 4, H 2O

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei; Tan, Keqin; Millar, Graeme J.; Palmer, Sara J.

    2012-01-01

    Some minerals are colloidal and show no X-ray diffraction patterns. Vibrational spectroscopy offers one of the few methods for the determination of the structure of these minerals. Among this group of minerals is pitticite, simply described as (Fe, AsO 4, SO 4, H 2O). In this work, the analogue of the mineral pitticite has been synthesised. The objective of this research is to determine the molecular structure of the mineral pitticite using vibrational spectroscopy. Raman and infrared bands are attributed to the AsO 43-, SO 42- and water stretching and bending vibrations. The Raman spectrum of the pitticite analogue shows intense peaks at 845 and 837 cm -1 assigned to the AsO 43- stretching vibrations. Raman bands at 1096 and 1182 cm -1 are attributed to the SO 42- antisymmetric stretching bands. Raman spectroscopy offers a useful method for the analysis of such colloidal minerals.

  14. The Volcano Adventure Guide

    NASA Astrophysics Data System (ADS)

    Goff, Fraser

    2005-05-01

    Adventure travels to volcanoes offer chance encounters with danger, excitement, and romance, plus opportunities to experience scientific enlightenment and culture. To witness a violently erupting volcano and its resulting impacts on landscape, climate, and humanity is a powerful personal encounter with gigantic planetary forces. To study volcano processes and products during eruptions is to walk in the footsteps of Pliny himself. To tour the splendors and horrors of 25 preeminent volcanoes might be the experience of a lifetime, for scientists and nonscientists alike. In The Volcano Adventure Guide, we now have the ultimate tourist volume to lead us safely to many of the world's famous volcanoes and to ensure that we will see the important sites at each one.

  15. Stress, strain rate and anisotropy in Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Savage, M. K.; Aoki, Y.; Unglert, K.; Ohkura, T.; Umakoshi, K.; Shimizu, H.; Iguchi, M.; Tameguri, T.; Ohminato, T.; Mori, J.

    2016-04-01

    Seismic anisotropy, the directional dependence of wave speeds, may be caused by stress-oriented cracks or by strain-oriented minerals, yet few studies have quantitatively compared anisotropy to stress and strain over large regions. Here we compare crustal stress and strain rates on the Island of Kyushu, Japan, as measured from inversions of focal mechanisms, GPS and shear wave splitting. Over 85,000 shear wave splitting measurements from local and regional earthquakes are obtained from the NIED network between 2004 and 2012, and on Aso, Sakurajima, Kirishima and Unzen volcano networks. Strain rate measurements are made from the Japanese Geonet stations. JMA-determined S arrival times processed with the MFAST shear wave splitting code measure fast polarisations (Φ), related to the orientation of the anisotropic medium and time delays (dt), related to the path length and the percent anisotropy. We apply the TESSA 2-D delay time tomography and spatial averaging code to the highest quality events, which have nearly vertical incidence angles, separating the 3455 shallow (depth < 40 km) from the 4957 deep (> = 40 km) earthquakes. Using square grids with 30 km sides for all the inversions, the best correlations are observed between splitting from shallow earthquakes and stress. Axes of maximum horizontal stress (SHmax) and Φ correlate with a coefficient c of 0.56, significant at the 99% confidence level. Their mean difference is 31.9°. Axes of maximum compressional strain rate and SHmax are also well aligned, with an average difference of 28°, but they do not correlate with each other, meaning that where they differ, the difference is not systematic. Anisotropy strength is negatively correlated with the stress ratio parameter determined from focal mechanism inversion (c = - 0.64; significant at the 99% confidence level). The anisotropy and stress results are consistent with stress-aligned microcracks in the crust in a dominantly strike-slip regime. Eigenvalues of

  16. A Rapid Turn-around, Scalable Big Data Processing Capability for the JPL Airborne Snow Observatory (ASO) Mission

    NASA Astrophysics Data System (ADS)

    Mattmann, C. A.

    2014-12-01

    The JPL Airborne Snow Observatory (ASO) is an integrated LIDAR and Spectrometer measuring snow depth and rate of snow melt in the Sierra Nevadas, specifically, the Tuolumne River Basin, Sierra Nevada, California above the O'Shaughnessy Dam of the Hetch Hetchy reservoir, and the Uncompahgre Basin, Colorado, amongst other sites. The ASO data was delivered to water resource managers from the California Department of Water Resources in under 24 hours from the time that the Twin Otter aircraft landed in Mammoth Lakes, CA to the time disks were plugged in to the ASO Mobile Compute System (MCS) deployed at the Sierra Nevada Aquatic Research Laboratory (SNARL) near the airport. ASO performed weekly flights and each flight took between 500GB to 1 Terabyte of raw data, which was then processed from level 0 data products all the way to full level 4 maps of Snow Water Equivalent, albedo mosaics, and snow depth from LIDAR. These data were produced by Interactive Data analysis Language (IDL) algorithms which were then unobtrusively and automatically integrated into an Apache OODT and Apache Tika based Big Data processing system. Data movement was both electronic and physical including novel uses of LaCie 1 and 2 TeraByte (TB) data bricks and deployment in rugged terrain. The MCS was controlled remotely from the Jet Propulsion Laboratory, California Institute of Technology (JPL) in Pasadena, California on behalf of the National Aeronautics and Space Administration (NASA). Communication was aided through the use of novel Internet Relay Chat (IRC) command and control mechanisms and through the use of the Notifico open source communication tools. This talk will describe the high powered, and light-weight Big Data processing system that we developed for ASO and its implications more broadly for airborne missions at NASA and throughout the government. The lessons learned from ASO show the potential to have a large impact in the development of Big Data processing systems in the years

  17. Synthesis and crystal structure of Na4Ni7(AsO4)6

    PubMed Central

    David, Rénald

    2016-01-01

    The title compound, tetra­sodium hepta­nickel hexa­arsenate, was obtained by ceramic synthesis and crystallizes in the monoclinic space group C2/m. The asymmetric unit contains seven Ni atoms of which two have site symmetry 2/m and three site symmetry 2, four As atoms of which two have site symmetry m and two site symmetry 2, three Na atoms of which two have site symmetry 2, and fifteen O atoms of which four have site symmetry m. The structure of Na4Ni7(AsO4)6 is made of layers of Ni octa­hedra and As tetra­hedra assembled in sheets parallel to the bc plane. These layers are inter­connected by corner-sharing between NiO6 octa­hedra and AsO4 tetra­hedra. This linkage creates tunnels running along the c axis in which the Na atoms are located. This arrangement is similar to the one observed in Na4Ni7(PO4)6, but the layers of the two compounds are slightly different because of the disorder of one of the Ni sites in the structure of the title compound. PMID:27308006

  18. Yellowstone Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Lowenstern, Jacob

    2008-01-01

    Eruption of Yellowstone's Old Faithful Geyser. Yellowstone hosts the world's largest and most diverse collection of natural thermal features, which are the surface expression of magmatic heat at shallow depths in the crust. The Yellowstone system is monitored by the Yellowstone Volcano Observatory (YVO), a partnership among the U.S. Geological Survey (USGS), Yellowstone National Park, and the University of Utah. YVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Yellowstone and YVO at http://volcanoes.usgs.gov/yvo.

  19. Mud volcanoes on Mars?

    NASA Technical Reports Server (NTRS)

    Komar, Paul D.

    1991-01-01

    The term mud volcano is applied to a variety of landforms having in common a formation by extrusion of mud from beneath the ground. Although mud is the principal solid material that issues from a mud volcano, there are many examples where clasts up to boulder size are found, sometimes thrown high into the air during an eruption. Other characteristics of mud volcanoes (on Earth) are discussed. The possible presence of mud volcanoes, which are common and widespread on Earth, on Mars is considered.

  20. Alaska Volcano Observatory at 20

    NASA Astrophysics Data System (ADS)

    Eichelberger, J. C.

    2008-12-01

    The Alaska Volcano Observatory (AVO) was established in 1988 in the wake of the 1986 Augustine eruption through a congressional earmark. Even within the volcanological community, there was skepticism about AVO. Populations directly at risk in Alaska were small compared to Cascadia, and the logistical costs of installing and maintaining monitoring equipment were much higher. Questions were raised concerning the technical feasibility of keeping seismic stations operating through the long, dark, stormy Alaska winters. Some argued that AVO should simply cover Augustine with instruments and wait for the next eruption there, expected in the mid 90s (but delayed until 2006), rather than stretching to instrument as many volcanoes as possible. No sooner was AVO in place than Redoubt erupted and a fully loaded passenger 747 strayed into the eruption cloud between Anchorage and Fairbanks, causing a powerless glide to within a minute of impact before the pilot could restart two engines and limp into Anchorage. This event forcefully made the case that volcano hazard mitigation is not just about people and infrastructure on the ground, and is particularly important in the heavily traveled North Pacific where options for flight diversion are few. In 1996, new funding became available through an FAA earmark to aggressively extend volcano monitoring far into the Aleutian Islands with both ground-based networks and round-the-clock satellite monitoring. Beyond the Aleutians, AVO developed a monitoring partnership with Russians volcanologists at the Institute of Volcanology and Seismology in Petropavlovsk-Kamchatsky. The need to work together internationally on subduction phenomena that span borders led to formation of the Japan-Kamchatka-Alaska Subduction Processes (JKASP) consortium. JKASP meets approximately biennially in Sapporo, Petropavlovsk, and Fairbanks. In turn, these meetings and support from NSF and the Russian Academy of Sciences led to new international education and

  1. Reunion Island Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On January 16, 2002, lava that had begun flowing on January 5 from the Piton de la Fournaise volcano on the French island of Reunion abruptly decreased, marking the end of the volcano's most recent eruption. These false color MODIS images of Reunion, located off the southeastern coast of Madagascar in the Indian Ocean, were captured on the last day of the eruption (top) and two days later (bottom). The volcano itself is located on the southeast side of the island and is dark brown compared to the surrounding green vegetation. Beneath clouds (light blue) and smoke, MODIS detected the hot lava pouring down the volcano's flanks into the Indian Ocean. The heat, detected by MODIS at 2.1 um, has been colored red in the January 16 image, and is absent from the lower image, taken two days later on January 18, suggesting the lava had cooled considerably even in that short time. Earthquake activity on the northeast flank continued even after the eruption had stopped, but by January 21 had dropped to a sufficiently low enough level that the 24-hour surveillance by the local observatory was suspended. Reunion is essentially all volcano, with the northwest portion of the island built on the remains of an extinct volcano, and the southeast half built on the basaltic shield of 8,630-foot Piton de la Fournaise. A basaltic shield volcano is one with a broad, gentle slope built by the eruption of fluid basalt lava. Basalt lava flows easily across the ground remaining hot and fluid for long distances, and so they often result in enormous, low-angle cones. The Piton de la Fournaise is one of Earth's most active volcanoes, erupting over 150 times in the last few hundred years, and it has been the subject of NASA research because of its likeness to the volcanoes of Mars. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  2. Stabilin-1 and Stabilin-2 are specific receptors for the cellular internalization of phosphorothioate-modified antisense oligonucleotides (ASOs) in the liver

    PubMed Central

    Miller, Colton M.; Donner, Aaron J.; Blank, Emma E.; Egger, Andrew W.; Kellar, Brianna M.; Østergaard, Michael E.; Seth, Punit P.; Harris, Edward N.

    2016-01-01

    Phosphorothioate (PS)-modified antisense oligonucleotides (ASOs) have been extensively investigated over the past three decades as pharmacological and therapeutic agents. One second generation ASO, Kynamro™, was recently approved by the FDA for the treatment of homozygous familial hypercholesterolemia and over 35 second generation PS ASOs are at various stages of clinical development. In this report, we show that the Stabilin class of scavenger receptors, which were not previously thought to bind DNA, do bind and internalize PS ASOs. With the use of primary cells from mouse and rat livers and recombinant cell lines each expressing Stabilin-1 and each isoform of Stabilin-2 (315-HARE and 190-HARE), we have determined that PS ASOs bind with high affinity and these receptors are responsible for bulk, clathrin-mediated endocytosis within the cell. Binding is primarily dependent on salt-bridge formation and correct folding of the intact protein receptor. Increased internalization rates also enhanced ASO potency for reducing expression of the non-coding RNA Malat-1, in Stabilin-expressing cell lines. A more thorough understanding of mechanisms by which ASOs are internalized in cells and their intracellular trafficking pathways will aid in the design of next generation antisense agents with improved therapeutic properties. PMID:26908652

  3. Tokyo, Japan

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Tokyo, (35.5N, 140.0E) the capital city of Japan, Tokyo Bay and the neighboring cities of Yokohama, Kawasaki and Chiba are seen in this view of Japan. This great international seaport facility covers almost all of the bayfront and is home to over thirty million people.

  4. Combined use of RFLP and PCR-ASO typing for HLA-DR-Dw and DQw typing.

    PubMed

    Bignon, J D; Bidwell, J L

    1991-01-01

    Due to some limitations of restriction fragment length polymorphism (RFLP) analysis in HLA-DR-DQ typing, we present a combined use of RFLP and polymerase chain reaction (PCR)-allele-specific oligonucleotide (ASO) typing. This scheme consists in selectively amplifying the few RFLP ill-defined genes (DR1/DR'Br' and DR4-Dw subsets) using PCR with allele specific primers to avoid cross-hybridization. PMID:1676910

  5. Evolution of the 120 ka caldera-forming eruption of Kutcharo volcano, eastern Hokkaido, Japan: Geologic and petrologic evidence for multiple vent systems and rapid generation of pyroclastic flow

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takeshi; Matsumoto, Akiko; Nakagawa, Mitsuhiro

    2016-07-01

    We investigated the eruptive sequence and temporal evolution of juvenile materials during the 120 ka Kutcharo pumice flow IV (Kp IV) eruption, which was the most voluminous (175 km3: bulk volume) caldera-forming eruption of Kutcharo volcano. The eruptive deposits are divided into four units in ascending order. Unit 1 is widely dispersed and consists of silt-sized, cohesive ash. Unit 2 is a thin, moderately sorted pumice fall deposit with a restricted distribution and small volume (< 0.2 km3). Unit 3, consisting of widely distributed ignimbrite, is the most voluminous. Unit 4 is also composed of pyroclastic flow deposits, but its distribution is limited to the northwest side of the caldera. Juvenile materials consist mainly of rhyolite pumice (74%-78% SiO2) associated with a minor amount of scoria (52%-73% SiO2) that are found only northwest of the caldera in Unit 3 and Unit 4. These scoriae can be classified on the basis of the P2O5 contents of their matrix glass into low-P, medium-P, and high-P types, which are almost entirely restricted to the lower part of Unit 3, Unit 4, and the upper part of Unit 3, respectively. These three types display distinct mixing trends with the rhyolitic compositions in SiO2-P2O5 variation diagrams. This evidence indicates that three distinct mafic magmas were independently and intermittently injected into the main body of silicic magma to erupt from the northwestern part of the magma system. Mafic injections did not occur in the southern part of the magma system. This petrologic evidence implies that the northwestern and southeastern flows of Unit 3 are heterotopic, contemporaneous products derived from multiple vent systems. Although Unit 2 was derived from an eruptive column, its volume is very small compared to Plinian fall deposits of typical caldera-forming eruptions. In our interpretation, the activity of the Kp IV eruption reached its climax rapidly, depositing Unit 3, without first producing a stable Plinian column. The

  6. Sequence and eruptive style of the 1783 eruption of Asama Volcano, central Japan: a case study of an andesitic explosive eruption generating fountain-fed lava flow, pumice fall, scoria flow and forming a cone

    NASA Astrophysics Data System (ADS)

    Yasui, Maya; Koyaguchi, Takehiro

    The 3-month long eruption of Asama volcano in 1783 produced andesitic pumice falls, pyroclastic flows, lava flows, and constructed a cone. It is divided into six episodes on the basis of waxing and waning inferred from records made during the eruption. Episodes 1 to 4 were intermittent Vulcanian or Plinian eruptions, which generated several pumice fall deposits. The frequency and intensity of the eruption increased dramatically in episode 5, which started on 2 August, and culminated in a final phase that began on the night of 4 August, lasting for 15 h. This climactic phase is further divided into two subphases. The first subphase is characterized by generation of a pumice fall, whereas the second one is characterized by abundant pyroclastic flows. Stratigraphic relationships suggest that rapid growth of a cone and the generation of lava flows occurred simultaneously with the generation of both pumice falls and pyroclastic flows. The volumes of the ejecta during the first and second subphases are 0.21 km3 (DRE) and 0.27 km3 (DRE), respectively. The proportions of the different eruptive products are lava: cone: pumice fall=84:11:5 in the first subphase and lava: cone: pyroclastic flow=42:2:56 in the second subphase. The lava flows in this eruption consist of three flow units (L1, L2, and L3) and they characteristically possess abundant broken phenocrysts, and show extensive "welding" texture. These features, as well as ghost pyroclastic textures on the surface, indicate that the lava was a fountain-fed clastogenic lava. A high discharge rate for the lava flow (up to 106 kg/s) may also suggest that the lava was initially explosively ejected from the conduit. The petrology of the juvenile materials indicates binary mixing of an andesitic magma and a crystal-rich dacitic magma. The mixing ratio changed with time; the dacitic component is dominant in the pyroclasts of the first subphase of the climactic phase, while the proportion of the andesitic component increases in

  7. Stereo Image of Mt. Usu Volcano

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On April 3, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra Satellite captured this image of the erupting Mt. Usu volcano in Hokkaido, Japan. This anaglyph stereo image is of Mt Usu volcano. On Friday, March 31, more than 15,000 people were evacuated by helicopter, truck and boat from the foot of Usu, that began erupting from the northwest flank, shooting debris and plumes of smoke streaked with blue lightning thousands of feet in the air. Although no lava gushed from the mountain, rocks and ash continued to fall after the eruption. The region was shaken by thousands of tremors before the eruption. People said they could taste grit from the ash that was spewed as high as 2,700 meters (8,850 ft) into the sky and fell to coat surrounding towns with ash. A 3-D view can be obtained by looking through stereo glasses, with the blue film through your left eye and red film with your right eye at the same time. North is on your right hand side. For more information, see When Rivers of Rock Flow ASTER web page Image courtesy of MITI, ERSDAC, JAROS, and the U.S./Japan ASTER Science Team

  8. Heavy atom nitroxyl radicals. II: Spectroscopic detection of H2As=O, the prototypical arsenyl free radical

    NASA Astrophysics Data System (ADS)

    He, Sheng-Gui; Sunahori, Fumie X.; Yang, Jie; Clouthier, Dennis J.

    2009-09-01

    The previously unknown arsenyl (H2AsO) free radical has been identified in the gas phase through a combination of laser-induced fluorescence and single vibronic level emission spectroscopy in a supersonic expansion. Three isotopologues, H2AsO, HDAsO, and D2AsO have been detected as products of an electric discharge in mixtures of arsine or deuterated arsines, CO2, and argon. The observed spectra are assigned as due to the B˜ A2'-X˜ A2' electronic transition in which an electron in the ground state π orbital is promoted to the π∗ orbital. Rotational analysis of high-resolution spectra proves that the radical is nonplanar in both electronic states with the following r0 structures: r″(As-H)=1.513(4) Å, r″(As-O)=1.672(1) Å, θ″(HAsH)=101.8(4)°, ground state out-of-plane angle=63.1°; r'(As-H)=1.525(10) Å, r'(As-O)=1.806(3) Å, θ'(HAsH)=93.4(10)°, and excited state out-of-plane angle=70.7°. Small hyperfine splittings in the spectra have enabled the determination of the arsenic Fermi contact parameter in both states. The results of our ab initio studies of the ground and excited state of this radical (see immediately preceding paper) are in good agreement with the spectroscopic analysis.

  9. Disposition and Pharmacology of a GalNAc3-conjugated ASO Targeting Human Lipoprotein (a) in Mice.

    PubMed

    Yu, Rosie Z; Graham, Mark J; Post, Noah; Riney, Stan; Zanardi, Thomas; Hall, Shannon; Burkey, Jennifer; Shemesh, Colby S; Prakash, Thazha P; Seth, Punit P; Swayze, Eric E; Geary, Richard S; Wang, Yanfeng; Henry, Scott

    2016-01-01

    Triantennary N-acetyl galactosamine (GalNAc3)-conjugated antisense oligonucleotides (ASOs) have greatly improved potency via receptor-mediated uptake. In the present study, the in vivo pharmacology of a 2'-O-(2-methoxyethyl)-modified ASO conjugated with GalNAc3 (ISIS 681257) together with its unmodified congener (ISIS 494372) targeting human apolipoprotein (a) (apo(a)), were studied in human LPA transgenic mice. Further, the disposition kinetics of ISIS 681257 was studied in CD-1 mice. ISIS 681257 demonstrated over 20-fold improvement in potency over ISIS 494372 as measured by liver apo(a) mRNA and plasma apo(a) protein levels. Following subcutaneous (SC) dosing, ISIS 681257 cleared rapidly from plasma and distributed to tissues. Intact ISIS 681257 was the major full-length oligonucleotide species in plasma. In tissues, however, GalNAc sugar moiety was rapidly metabolized and unconjugated ISIS 681257 accounted > 97% of the total exposure, which was then cleared slowly from tissues with a half-life of 7-8 days, similar to the half-life in plasma. ISIS 681257 is highly bound to plasma proteins (> 94% bound), which limited its urinary excretion. This study confirmed dose-dependent exposure to the parent drug ISIS 681257 in plasma and rapid conversion to unconjugated ASO in tissues. Safety data and the extended half-life support its further development and weekly dosing in phase 1 clinical studies. PMID:27138177

  10. Analysis of Snow Albedo, Grain Size and Radiative Forcing based on the Airborne Snow Observatory (ASO) Imaging Spectroscopy Data

    NASA Astrophysics Data System (ADS)

    Seidel, F. C.; Painter, T. H.

    2013-12-01

    Climate is expected to be most vulnerable in mountainous and arctic regions where the atmosphere and the hydrosphere are directly linked to the cryosphere. A combination of modeling and large-scale observational efforts is required to investigate related scientific questions. NASA's Airborne Snow Observatory (ASO) at the Jet Propulsion Laboratory addresses some of these needs by establishing new quantitative observational capabilities in regional mapping of mountain snow properties. In addition, ASO's key products showed that we are able to achieve societal benefits by improving water resources management. We will show the first analysis of snow optical products (albedo, grain size, and radiative forcing) from the spring 2013 ASO campaign in the Sierra Nevada, CA, USA. In addition, we will present the retrieval methods used to derive these products based on airborne imaging spectroscopy, LiDAR, as well as radiative transfer models. The preliminary findings provide new important insights into the temporal and spatial aspects of Western US mountain snow and its melt.

  11. Volcano seismicity in Alaska

    NASA Astrophysics Data System (ADS)

    Buurman, Helena

    I examine the many facets of volcano seismicity in Alaska: from the short-lived eruption seismicity that is limited to only the few weeks during which a volcano is active, to the seismicity that occurs in the months following an eruption, and finally to the long-term volcano seismicity that occurs in the years in which volcanoes are dormant. I use the rich seismic dataset that was recorded during the 2009 eruption of Redoubt Volcano to examine eruptive volcano seismicity. I show that the progression of magma through the conduit system at Redoubt could be readily tracked by the seismicity. Many of my interpretations benefited greatly from the numerous other datasets collected during the eruption. Rarely was there volcanic activity that did not manifest itself in some way seismically, however, resulting in a remarkably complete chronology within the seismic record of the 2009 eruption. I also use the Redoubt seismic dataset to study post-eruptive seismicity. During the year following the eruption there were a number of unexplained bursts of shallow seismicity that did not culminate in eruptive activity despite closely mirroring seismic signals that had preceded explosions less than a year prior. I show that these episodes of shallow seismicity were in fact related to volcanic processes much deeper in the volcanic edifice by demonstrating that earthquakes that were related to magmatic activity during the eruption were also present during the renewed shallow unrest. These results show that magmatic processes can continue for many months after eruptions end, suggesting that volcanoes can stay active for much longer than previously thought. In the final chapter I characterize volcanic earthquakes on a much broader scale by analyzing a decade of continuous seismic data across 46 volcanoes in the Aleutian arc to search for regional-scale trends in volcano seismicity. I find that volcanic earthquakes below 20 km depth are much more common in the central region of the arc

  12. A European research infrastructure for the aerosol study on a continental scale: EARLINET-ASOS

    NASA Astrophysics Data System (ADS)

    Amodeo, Aldo; Pappalardo, Gelsomina; Bösenberg, Jens; Ansmann, Albert; Apituley, Arnoud; Alados-Arboledas, Lucas; Balis, Dimitris; Böckmann, Christine; Chaikovsky, Anatoly; Comeron, Adolfo; Freudenthaler, Volker; Gustaffson, Ove; Hansen, Georg; Mitev, Valentin; Nicolae, Doina; Papayannis, Alexandros; Perrone, Maria Rita; Pietruczuk, Aleksander; Pujadas, Manuel; Putaud, Jean-Philippe; Ravetta, Francois; Rizi, Vincenzo; Simeonov, Valentin; Spinelli, Nicola; Stoyanov, Dimitar; Trickl, Thomas; Wiegner, Matthias

    2007-10-01

    The present knowledge of the aerosol distribution is not sufficient to estimate the aerosol influence on global and regional environmental conditions and climate. This observational gap can be closed by using advanced laser remote sensing. EARLINET (European Aerosol Research Lidar Network) is the first aerosol lidar network, established in 2000, with the main goal to provide a comprehensive, quantitative, and statistically significant database for the aerosol distribution on a continental scale. EARLINET is a coordinated network of European stations (25 at present) using advanced lidar methods for the vertical profiling of aerosols. The network activity is based on simultaneous scheduled measurements, a rigorous quality assurance program addressing both instruments and evaluation algorithms, and a standardised data exchange format. Further observations are performed to monitor special events. EARLINET-ASOS (Advanced Sustainable Observation System) is a five year EC Project started in 2006, based on the EARLINET infrastructure. The main objectives are: to make EARLINET a world-leading instrument for the observation of the 4-D aerosol distribution on continental scale; to foster aerosol-related process studies, validation of satellite sensors, model development and validation, assimilation of aerosol data into operational models; and to build a comprehensive climatology of the aerosol distribution.

  13. Remote Monitoring of Aerosol Layers over Sofia in the Frame of EARLINET-ASOS Project

    NASA Astrophysics Data System (ADS)

    Grigorov, Ivan; Kolarov, Georgi; Stoyanov, Dimitar

    2010-01-01

    In this work we present some results of lidar remote sensing of aerosol layers in the atmosphere in Sofia region. The investigations were made using a lidar system equipped with a CuBr-vapor laser with high pulse repetition of 13 kHz and receiver in photon counting mode. These measurements were performed in frame of the project European Aerosol Research Lidar Network—Advanced Sustainable Observation System (EARLINET—ASOS). For some of presented results a conclusion about atmospheric aerosol's origins was made upon analyses of the information about the weather condition during the lidar measurements. Such information was obtained by the weather-forecast maps provided by the Atmospheric Modeling and Weather Forecasting Group of NTUA and the Forecast system of Barcelona Supercomputing Centre and accessible via Internet. Additional information is provided by calculations of the backward air mass trajectories, using online software of NOAA about HYSPLIT model (HYbrid Single-Particle Lagrangian Integrated Trajectory). A common database that automatically collects the data products provided by the individual lidar stations is build and makes data of measurements available to the scientific community.

  14. Japan Smoke

    Atmospheric Science Data Center

    2013-04-16

    article title:  Smoke Plume from Industrial Fires in Miyagi Prefecture, Japan     ... 2011, and its subsequent tsunami, several oil refineries and industrial complexes caught fire, including facilities in the Port of Sendai ...

  15. Volcanoes: Coming Up from Under.

    ERIC Educational Resources Information Center

    Science and Children, 1980

    1980-01-01

    Provides specific information about the eruption of Mt. St. Helens in March 1980. Also discusses how volcanoes are formed and how they are monitored. Words associated with volcanoes are listed and defined. (CS)

  16. The diversity of mud volcanoes in the landscape of Azerbaijan

    NASA Astrophysics Data System (ADS)

    Rashidov, Tofig

    2014-05-01

    As the natural phenomenon the mud volcanism (mud volcanoes) of Azerbaijan are known from the ancient times. The historical records describing them are since V century. More detail study of this natural phenomenon had started in the second half of XIX century. The term "mud volcano" (or "mud hill") had been given by academician H.W. Abich (1863), more exactly defining this natural phenomenon. All the previous definitions did not give such clear and capacious explanation of it. In comparison with magmatic volcanoes, globally the mud ones are restricted in distribution; they mainly locate within the Alpine-Himalayan, Pacific and Central Asian mobile belts, in more than 30 countries (Columbia, Trinidad Island, Italy, Romania, Ukraine, Georgia, Azerbaijan, Turkmenistan, Iran, Pakistan, Indonesia, Burma, Malaysia, etc.). Besides it, the zones of mud volcanoes development are corresponded to zones of marine accretionary prisms' development. For example, the South-Caspian depression, Barbados Island, Cascadia (N.America), Costa-Rica, Panama, Japan trench. Onshore it is Indonesia, Japan, and Trinidad, Taiwan. The mud volcanism with non-accretionary conditions includes the areas of Black Sea, Alboran Sea, the Gulf of Mexico (Louisiana coast), Salton Sea. But new investigations reveal more new mud volcanoes and in places which were not considered earlier as the traditional places of mud volcanoes development (e.g. West Nile Rive delta). Azerbaijan is the classic region of mud volcanoes development. From over 800 world mud volcanoes there are about 400 onshore and within the South-Caspian basin, which includes the territory of East Azerbaijan (the regions of Shemakha-Gobustan and Low-Kura River, Absheron peninsula), adjacent water area of South Caspian (Baku and Absheron archipelagoes) and SW Turkmenistan and represents an area of great downwarping with thick (over 25 km) sedimentary series. Generally, in the modern relief the mud volcanoes represent more or less large uplifts

  17. Erupting Volcano Mount Etna

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Expedition Five crew members aboard the International Space Station (ISS) captured this overhead look at the smoke and ash regurgitated from the erupting volcano Mt. Etna on the island of Sicily, Italy in October 2002. Triggered by a series of earthquakes on October 27, 2002, this eruption was one of Etna's most vigorous in years. This image shows the ash plume curving out toward the horizon. The lighter-colored plumes down slope and north of the summit seen in this frame are produced by forest fires set by flowing lava. At an elevation of 10,990 feet (3,350 m), the summit of the Mt. Etna volcano, one of the most active and most studied volcanoes in the world, has been active for a half-million years and has erupted hundreds of times in recorded history.

  18. Volcano Near Pavonis Mons

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-549, 19 November 2003

    The volcanic plains to the east, southeast, and south of the giant Tharsis volcano, Pavonis Mons, are dotted by dozens of small volcanoes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 2.1oS, 109.1oW. The elongate depression in the lower left (southwest) quarter of the image is the collapsed vent area for this small, unnamed volcano. A slightly sinuous, leveed channel runs from the depression toward the upper right (north-northeast); this is the trace of a collapsed lava tube. The entire scene has been mantled by dust, such that none of the original volcanic rocks are exposed--except minor occurrences on the steepest slopes in the vent area. The scene is 3 km (1.9 mi) wide and illuminated by sunlight from the left/upper left.

  19. Volcano-electromagnetic effects

    USGS Publications Warehouse

    Johnston, Malcolm J. S.

    2007-01-01

    Volcano-electromagnetic effects—electromagnetic (EM) signals generated by volcanic activity—derive from a variety of physical processes. These include piezomagnetic effects, electrokinetic effects, fluid vaporization, thermal demagnetization/remagnetization, resistivity changes, thermochemical effects, magnetohydrodynamic effects, and blast-excited traveling ionospheric disturbances (TIDs). Identification of different physical processes and their interdependence is often possible with multiparameter monitoring, now common on volcanoes, since many of these processes occur with different timescales and some are simultaneously identified in other geophysical data (deformation, seismic, gas, ionospheric disturbances, etc.). EM monitoring plays an important part in understanding these processes.

  20. Using thermal remanent magnetisation (TRM) to distinguish block and ash flow and debris flow deposits, and to estimate their emplacement temperature: 1991-1995 lava dome eruption at Mt. Unzen Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Uehara, D.; Cas, R. A. F.; Folkes, C.; Takarada, S.; Oda, H.; Porreca, M.

    2015-09-01

    The 1991-1995 Mt. Unzen eruption (Kyushu, Japan) produced 13 lava domes, approximately 9400 block and ash pyroclastic flows (BAF) resulting from lava dome collapse events and syn- and post-dome collapse debris flow (DF) events. In the field, it can be very difficult to distinguish from field facies characteristics which deposits are primary hot BAF, cold BAF or rock avalanche, or secondary DF deposits. In this study we use a combination of field observations and thermal remanent magnetisation (TRM) analysis of juvenile, lava dome derived clasts from seven deposits of the 1991-1995 Mt. Unzen eruption in order to distinguish between primary BAF deposits and secondary DF deposits and to determine their emplacement temperature. Four major TRM patterns were identified: (1) Type I: clasts with a single magnetic component oriented parallel to the Earth's magnetic field at time and site of emplacement. This indicates that these deposits were deposited at very high temperature, between the Curie temperature of magnetite (~ 540 °C) and the glass transition temperature of the lava dome (~ 745 °C). These clasts are found in high temperature BAF deposits. (2) Type II: clasts with two magnetic components of magnetisation. The lower temperature magnetic components are parallel to the Earth's magnetic field at time of the Unzen eruption. Temperature estimations for these deposits can range from 80 to 540 °C. We found this paleomagnetic behaviour in moderate temperature BAF or warm DF deposits. (3) Type III: clasts with three magnetic components, with a lower temperature component oriented parallel to the Earth's magnetic field at Unzen. The individual clast temperatures estimated for this kind of deposit are usually less than 300 °C. We interpret this paleomagnetic behaviour as the effect of different thermal events during their emplacement history. There are several interpretations for this paleomagnetic behaviour including remobilisation of moderate temperature BAF, warm DF

  1. Volcanoes and the Environment

    NASA Astrophysics Data System (ADS)

    Marti, Edited By Joan; Ernst, Gerald G. J.

    2005-10-01

    Volcanoes and the Environment is a comprehensive and accessible text incorporating contributions from some of the world's authorities in volcanology. This book is an indispensable guide for those interested in how volcanism affects our planet's environment. It spans a wide variety of topics from geology to climatology and ecology; it also considers the economic and social impacts of volcanic activity on humans. Topics covered include how volcanoes shape the environment, their effect on the geological cycle, atmosphere and climate, impacts on health of living on active volcanoes, volcanism and early life, effects of eruptions on plant and animal life, large eruptions and mass extinctions, and the impact of volcanic disasters on the economy. This book is intended for students and researchers interested in environmental change from the fields of earth and environmental science, geography, ecology and social science. It will also interest policy makers and professionals working on natural hazards. An all-inclusive text that goes beyond the geological working of volcanoes to consider their environmental and sociological impacts Each chapter is written by one of the world's leading authorities on the subject Accessible to students and researchers from a wide variety of backgrounds

  2. Santa Maria Volcano, Guatemala

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The eruption of Santa Maria volcano in 1902 was one of the largest eruptions of the 20th century, forming a large crater on the mountain's southwest flank. Since 1922, a lava-dome complex, Santiaguito, has been forming in the 1902 crater. Growth of the dome has produced pyroclastic flows as recently as the 2001-they can be identified in this image. The city of Quezaltenango (approximately 90,000 people in 1989) sits below the 3772 m summit. The volcano is considered dangerous because of the possibility of a dome collapse such as one that occurred in 1929, which killed about 5000 people. A second hazard results from the flow of volcanic debris into rivers south of Santiaguito, which can lead to catastrophic flooding and mud flows. More information on this volcano can be found at web sites maintained by the Smithsonian Institution, Volcano World, and Michigan Tech University. ISS004-ESC-7999 was taken 17 February 2002 from the International Space Station using a digital camera. The image is provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Searching and viewing of additional images taken by astronauts and cosmonauts is available at the NASA-JSC Gateway to

  3. Monitoring active volcanoes

    USGS Publications Warehouse

    Tilling, R.I.

    1980-01-01

    One of the most spectacular, awesomely beautiful, and at times, most destructive displays of natural energy is an erupting volcano, belching fume and ash thousands of feet into the atmoshpehere and pouring out red-hot molten lava in fountains and streams. 

  4. The Volcano Adventure Guide

    NASA Astrophysics Data System (ADS)

    Lopes, Rosaly

    2005-02-01

    This guide contains vital information for anyone wishing to visit, explore, and photograph active volcanoes safely and enjoyably. Following an introduction that discusses eruption styles of different types of volcanoes and how to prepare for an exploratory trip that avoids volcanic dangers, the book presents guidelines to visiting 42 different volcanoes around the world. It is filled with practical information that includes tour itineraries, maps, transportation details, and warnings of possible non-volcanic dangers. Three appendices direct the reader to a wealth of further volcano resources in a volume that will fascinate amateur enthusiasts and professional volcanologists alike. Rosaly Lopes is a planetary geology and volcanology specialist at the NASA Jet Propulsion Laboratory in California. In addition to her curatorial and research work, she has lectured extensively in England and Brazil and written numerous popular science articles. She received a Latinas in Science Award from the Comision Feminil Mexicana Nacional in 1991 and since 1992, has been a co-organizer of the United Nations/European Space Agency/The Planetary Society yearly conferences on Basic Science for the Benefit of Developing Countries.

  5. Geology of Kilauea volcano

    SciTech Connect

    Moore, R.B. . Federal Center); Trusdell, F.A. . Hawaiian Volcano Observatory)

    1993-08-01

    This paper summarizes studies of the structure, stratigraphy, petrology, drill holes, eruption frequency, and volcanic and seismic hazards of Kilauea volcano. All the volcano is discussed, but the focus is on its lower east rift zone (LERZ) because active exploration for geothermal energy is concentrated in that area. Kilauea probably has several separate hydrothermal-convection systems that develop in response to the dynamic behavior of the volcano and the influx of abundant meteoric water. Important features of some of these hydrothermal-convection systems are known through studies of surface geology and drill holes. Observations of eruptions during the past two centuries, detailed geologic mapping, radiocarbon dating, and paleomagnetic secular-variation studies indicate that Kilauea has erupted frequently from its summit and two radial rift zones during Quaternary time. Petrologic studies have established that Kilauea erupts only tholeiitic basalt. Extensive ash deposits at Kilauea's summit and on its LERZ record locally violent, but temporary, disruptions of local hydrothermal-convection systems during the interaction of water or steam with magma. Recent drill holes on the LERZ provide data on the temperatures of the hydrothermal-convection systems, intensity of dike intrusion, porosity and permeability, and an increasing amount of hydrothermal alteration with depth. The prehistoric and historic record of volcanic and seismic activity indicates that magma will continue to be supplied to deep and shallow reservoirs beneath Kilauea's summit and rift zones and that the volcano will be affected by eruptions and earthquakes for many thousands of years. 71 refs., 2 figs.

  6. Nyamuragira Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nyamuragira volcano erupted on July 26, 2002, spewing lava high into the air along with a large plume of steam, ash, and sulfur dioxide. The 3,053-meter (10,013-foot) volcano is located in eastern Congo, very near that country's border with Rwanda. Nyamuragira is the smaller, more violent sibling of Nyiragongo volcano, which devastated the town of Goma with its massive eruption in January 2002. Nyamuragira is situated just 40 km (24 miles) northeast of Goma. This pair of images was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on July 26. The image on the left shows the scene in true color. The small purple box in the upper righthand corner marks the location of Nyamuragira's hot summit. The false-color image on the right shows the plume from the volcano streaming southwestward. This image was made using MODIS' channels sensitive at wavelengths from 8.5 to 11 microns. Red pixels indicate high concentrations of sulphur dioxide. Image courtesy Liam Gumley, Space Science and Engineering Center, University of Wisconsin-Madison

  7. Nyamuragira Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nyamuragira volcano erupted on July 26, 2002, spewing lava high into the air along with a large plume of steam, ash, and sulfur dioxide. The 3,053-meter (10,013-foot) volcano is located in eastern Congo, very near that country's border with Rwanda. Nyamuragira is the smaller, more violent sibling of Nyiragongo volcano, which devastated the town of Goma with its massive eruption in January 2002. Nyamuragira is situated just 40 km (24 miles) northeast of Goma. This true-color image was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on July 28, 2002. Nyamuragira is situated roughly in the center of this scene, roughly 100 km south of Lake Edward and just north of Lake Kivu (which is mostly obscured by the haze from the erupting volcano and the numerous fires burning in the surrounding countryside). Due south of Lake Kivu is the long, narrow Lake Tanganyika running south and off the bottom center of this scene.

  8. GPS and EDM monitoring of Unzen volcano ground deformation

    NASA Astrophysics Data System (ADS)

    Matsushima, Takeshi; Takagi, Akimichi

    2000-11-01

    Following 198 years of dormancy, an eruption started at Mt. Fugen, the main peak of Unzen volcano, in Kyushu, Japan, in November 1990. A dacite lava dome began to grow in May 1991. We installed the surveying points of GPS in 1992 around the lava dome in order to observe the ground deformation that accompanied the growth of the lava dome. In the winters of 1993 and 1994, we observed swift ground deformations that radiated from the vent of the volcano. It was presumed that rising magma accumulated and expanded the volcano body. After the lava effusion stopped in 1995, we also installed surveying points on the lava dome. EDM mirrors were permanently fixed to the large rocks with bolts. A GPS survey was carried out 2 or 3 times each year to estimate the 3-dimensional displacement. The result of the EDM survey showed that the baselines from the flank of the volcano were shortening 5 mm per day, and the result of the GPS survey showed that the displacement vector of the dome was parallel to the direction of the steepest slope of the old volcano body. This indicates that the inside of the lava dome is still very hot, and that deformation of the dome is viscous.

  9. Catalogue of Icelandic Volcanoes

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Gudmundsson, Magnus T.; Vogfjord, Kristin; Pagneux, Emmanuel; Oddsson, Bjorn; Barsotti, Sara; Karlsdottir, Sigrun

    2016-04-01

    The Catalogue of Icelandic Volcanoes is a newly developed open-access web resource in English intended to serve as an official source of information about active volcanoes in Iceland and their characteristics. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland GOSVÁ (commenced in 2012), as well as being part of the effort of FUTUREVOLC (2012-2016) on establishing an Icelandic volcano supersite. Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene (the time since the end of the last glaciation - approximately the last 11,500 years). In the last 50 years, over 20 eruptions have occurred in Iceland displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and the distribution lava and tephra. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in numerous scientific papers and other publications. In 2010, the International Civil Aviation Organisation (ICAO) funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU through the FP7 project FUTUREVOLC. The Catalogue of Icelandic Volcanoes is a collaboration of the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Civil Protection Department of the National Commissioner of the Iceland Police, with contributions from a large number of specialists in Iceland and elsewhere. The Catalogue is built up of chapters with texts and various

  10. Alaska - Russian Far East connection in volcano research and monitoring

    NASA Astrophysics Data System (ADS)

    Izbekov, P. E.; Eichelberger, J. C.; Gordeev, E.; Neal, C. A.; Chebrov, V. N.; Girina, O. A.; Demyanchuk, Y. V.; Rybin, A. V.

    2012-12-01

    The Kurile-Kamchatka-Alaska portion of the Pacific Rim of Fire spans for nearly 5400 km. It includes more than 80 active volcanoes and averages 4-6 eruptions per year. Resulting ash clouds travel for hundreds to thousands of kilometers defying political borders. To mitigate volcano hazard to aviation and local communities, the Alaska Volcano Observatory (AVO) and the Institute of Volcanology and Seismology (IVS), in partnership with the Kamchatkan Branch of the Geophysical Survey of the Russian Academy of Sciences (KBGS), have established a collaborative program with three integrated components: (1) volcano monitoring with rapid information exchange, (2) cooperation in research projects at active volcanoes, and (3) volcanological field schools for students and young scientists. Cooperation in volcano monitoring includes dissemination of daily information on the state of volcanic activity in neighboring regions, satellite and visual data exchange, as well as sharing expertise and technologies between AVO and the Kamchatkan Volcanic Eruption Response Team (KVERT) and Sakhalin Volcanic Eruption Response Team (SVERT). Collaboration in scientific research is best illustrated by involvement of AVO, IVS, and KBGS faculty and graduate students in mutual international studies. One of the most recent examples is the NSF-funded Partnerships for International Research and Education (PIRE)-Kamchatka project focusing on multi-disciplinary study of Bezymianny volcano in Kamchatka. This international project is one of many that have been initiated as a direct result of a bi-annual series of meetings known as Japan-Kamchatka-Alaska Subduction Processes (JKASP) workshops that we organize together with colleagues from Hokkaido University, Japan. The most recent JKASP meeting was held in August 2011 in Petropavlovsk-Kamchatsky and brought together more than 130 scientists and students from Russia, Japan, and the United States. The key educational component of our collaborative program

  11. Tracking the movement of Hawaiian volcanoes; Global Positioning System (GPS) measurement

    USGS Publications Warehouse

    Dvorak, J.J.

    1992-01-01

    At some well-studied volcanoes, surface movements of at least several centimeters take place out to distances of about 10 km from the summit of the volcano. Widespread deformation of this type is relatively easy to monitor, because the necessary survey stations can be placed at favorable sites some distance from the summit of the volcano. Examples of deformation of this type include Kilauea and Mauna Loa in Hawaii, Krafla in Iceland, Long Valley in California, Camp Flegrei in Italy, and Sakurajima in Japan. In contrast, surface movement at some other volcanoes, usually volcanoes with steep slopes, is restricted to places within about 1 km of their summits. Examples of this class of volcanoes include Mount St. Helens in Washington, Etna in Italy, and Tangkuban Parahu in Indonesia. Local movement on remote, rugged volcanoes of this type is difficult to observe using conventional methods of measuring ground movement, which generally require a clear line-of-sight between points of interest. However, a revolutionary new technique, called the Global Positional System (GPS), provides a very efficient, alternative method of making such measurements. GPS, which uses satellites and ground-based receivers to accurately record slight crustal movements, is rapidly becoming the method of choice to measure deformation at volcanoes

  12. Catalogue of Icelandic volcanoes

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Vogfjörd, Kristin; Tumi Gudmundsson, Magnus; Jonsson, Trausti; Oddsson, Björn; Reynisson, Vidir; Barsotti, Sara; Karlsdottir, Sigrun

    2015-04-01

    Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene. In the last 100 years, over 30 eruptions have occurred displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and their distribution. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in scientific papers and other publications. In 2010, the International Civil Aviation Organisation funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland (commenced in 2012), and the EU FP7 project FUTUREVOLC (2012-2016), establishing an Icelandic volcano Supersite. The Catalogue is a collaborative effort between the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Icelandic Civil Protection, with contributions from a large number of specialists in Iceland and elsewhere. The catalogue is scheduled for opening in the first half of 2015 and once completed, it will be an official publication intended to serve as an accurate and up to date source of information about active volcanoes in Iceland and their characteristics. The Catalogue is an open web resource in English and is composed of individual chapters on each of the volcanic systems. The chapters include information on the geology and structure of the volcano; the eruption history, pattern and products; the known precursory signals

  13. Geochemical fingerprint of the primary magma composition in the marine tephras originated from the Baegdusan and Ulleung volcanoes

    NASA Astrophysics Data System (ADS)

    Lim, Chungwan; Kim, Seonyoung; Lee, Changyeol

    2014-12-01

    The intraplate Baegdusan (Changbai) and Ulleung volcanoes located on the border of China, North Korea, and East/Japan Sea, respectively, have been explained by appeals to both hotspots and asthenospheric mantle upwelling (wet plume) caused by the stagnant Pacific plate. To understand the origin of the Baegdusan and Ulleung volcanism, we performed geochemical analyses on the tephra deposits in the East/Japan Sea basins originating from the Baegdusan and Ulleung volcanoes. The volcanic glass in the tephra from the Baegdusan and Ulleung volcanoes ranged from alkaline trachyte to peralkaline rhyolite and from phonolite to trachyte, respectively. The tephra from the two intraplate volcanoes showed highly enriched incompatible elements, such as Tb, Nb, Hf, and Ta, distinct from those of the ordinary arc volcanoes of the Japanese islands. The straddle distribution of the Th/Yb and Ta/Yb ratios of the tephra deposits from the Baegdusan volcano may originate from the alkali basaltic magma resulting from mixing between the wet plume from the stagnant Pacific plate in the transition zone and the overlying shallow asthenospheric mantle. In contrast, the deposits from the Ulleung volcano show a minor contribution of the stagnant slab to the basaltic magma, implying either partial melting of a more enriched mantle, smaller degrees of partial melting of a garnet-bearing mantle source, or a combination of both processes as the magma genesis. Our study indicated that the Baegdusan and Ulleung volcanoes have different magma sources and evolutionary histories.

  14. Anatahan Volcano, Mariana Islands

    NASA Technical Reports Server (NTRS)

    2008-01-01

    In the early hours of February 7, ASTER captured this nighttime thermal infrared image of an eruption of Anatahan Volcano in the central Mariana Islands. The summit of the volcano is bright indicating there is a very hot area there. Streaming to the west is an ash plume, visible by the red color indicating the presence of silicate-rich particles. Dark grey areas are clouds that appear colder than the ocean. Anatahan is a stratovolcano that started erupting in May 2003, forming a new crater.

    The image covers an area of 56.3 x 41.8 km, and is located 16 degrees north latitude and 145.6 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  15. 4D volcano gravimetry

    USGS Publications Warehouse

    Battaglia, Maurizio; Gottsmann, J.; Carbone, D.; Fernandez, J.

    2008-01-01

    Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast (hours to weeks), as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera (California, U.S.A.) and Campi Flegrei (Italy), careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological inter-pretations, particularly when the real crust surrounding the source is far from the homogeneous/ isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located (e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography). Applications at Teide volcano (Tenerife) and Campi Flegrei demonstrate the

  16. Shiveluch and Klyuchevskaya Volcanoes

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A distance of about 80 kilometers (50 miles) separates Shiveluch and Klyuchevskaya Volcanoes on Russia's Kamchatka Peninsula. Despite this distance, however, the two acted in unison on April 26, 2007, when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite caught them both erupting simultaneously. ASTER 'sees' a slightly different portion of the light spectrum than human eyes. Besides a portion of visible light, ASTER detects thermal energy, meaning it can detect volcanic activity invisible to human eyes. Inset in each image above is a thermal infrared picture of the volcano's summit. In these insets, dark red shows where temperatures are coolest, and yellowish-white shows where temperatures are hottest, heated by molten lava. Both insets show activity at the crater. In the case of Klyuchevskaya, some activity at the crater is also visible in the larger image. In the larger images, the landscapes around the volcanoes appear in varying shades of blue-gray. Dark areas on the snow surface are likely stains left over from previous eruptions of volcanic ash. Overhead, clouds dot the sky, casting their shadows on the snow, especially southeast of Shiveluch and northeast of Klyuchevskaya. To the northwest of Klyuchevskaya is a large bank of clouds, appearing as a brighter white than the snow surface. Shiveluch (sometimes spelled Sheveluch) and Klyuchevskaya (sometimes spelled Klyuchevskoy or Kliuchevskoi) are both stratovolcanoes composed of alternating layers of hardened lava, solidified ash, and rocks from earlier eruptions. Both volcanoes rank among Kamchatka's most active. Because Kamchatka is part of the Pacific 'Ring of Fire,' the peninsula experiences regular seismic activity as the Pacific Plate slides below other tectonic plates in the Earth's crust. Large-scale plate tectonic activity causing simultaneous volcanic eruptions in Kamchatka is not uncommon.

  17. Volcanic and geologic database projects of the Geological Survey of Japan (Invited)

    NASA Astrophysics Data System (ADS)

    Takarada, S.; Nakano, S.; Hoshizumi, H.; Itoh, J.; Urai, M.; Nishiki, K.

    2009-12-01

    Geological Survey of Japan (GSJ) is presently implementing the GEO-DB project, which aims to integrate all kinds of geological information in GSJ. GSJ published more than 50 CD-ROM series and established more than 20 databases at the Research Information Database (RIO-DB) of the National Institute of Advanced Industrial Science and Technology (AIST). Presently, four volcanic databases are open to the public: (1) Quaternary volcano database (RIO-DB), (2) Active volcano database (RIO-DB), and (3) ASTER satellite image database of major volcanoes. The Quaternary volcano database contains information such as volcanic type, history, age and pictures of more than 300 Quaternary volcanoes in Japan. More detailed volcanic information will be added to the database in the near future. The active volcano database contains information of active volcanoes in Japan such as the catalog of eruptive events during the last 10,000 years and geological maps of active volcanoes. The ASTER satellite image database provides sequential ASTER satellite image datasets of major volcanoes in the world. Collaboration between Quaternary and active volcano databases and the VOGRIPA project is the next important activity at the Geological Survey of Japan. The Geological Survey of Japan introduced the Integrated Geological Map Database (GeoMapDB) in 2006. The GeoMapDB is based on a WebGIS technology, which makes it possible to browse, overlay and search geological maps online. The database contains geological maps with scales ranging from 1:2 million to 1:25,000. Links to aforementioned volcanic database and active fault database in RIO-DB are also available. OneGeology is an international initiative of the geological surveys of the world and a flagship project of the ‘International Year of Planet Earth’. It aims to create dynamic geological map of the world available at the world wide web. Geological Surveys from 109 countries of the world are participating in this project. The Geological

  18. Volcanoes and climate

    NASA Technical Reports Server (NTRS)

    Toon, O. B.

    1982-01-01

    The evidence that volcanic eruptions affect climate is reviewed. Single explosive volcanic eruptions cool the surface by about 0.3 C and warm the stratosphere by several degrees. Although these changes are of small magnitude, there have been several years in which these hemispheric average temperature changes were accompanied by severely abnormal weather. An example is 1816, the "year without summer" which followed the 1815 eruption of Tambora. In addition to statistical correlations between volcanoes and climate, a good theoretical understanding exists. The magnitude of the climatic changes anticipated following volcanic explosions agrees well with the observations. Volcanoes affect climate because volcanic particles in the atmosphere upset the balance between solar energy absorbed by the Earth and infrared energy emitted by the Earth. These interactions can be observed. The most important ejecta from volcanoes is not volcanic ash but sulfur dioxide which converts into sulfuric acid droplets in the stratosphere. For an eruption with its explosive magnitude, Mount St. Helens injected surprisingly little sulfur into the stratosphere. The amount of sulfuric acid formed is much smaller than that observed following significant eruptions and is too small to create major climatic shifts. However, the Mount St. Helens eruption has provided an opportunity to measure many properties of volcanic debris not previously measured and has therefore been of significant value in improving our knowledge of the relations between volcanic activity and climate.

  19. Volcanoes generate devastating waves

    SciTech Connect

    Lockridge, P. )

    1988-01-01

    Although volcanic eruptions can cause many frightening phenomena, it is often the power of the sea that causes many volcano-related deaths. This destruction comes from tsunamis (huge volcano-generated waves). Roughly one-fourth of the deaths occurring during volcanic eruptions have been the result of tsunamis. Moreover, a tsunami can transmit the volcano's energy to areas well outside the reach of the eruption itself. Some historic records are reviewed. Refined historical data are increasingly useful in predicting future events. The U.S. National Geophysical Data Center/World Data Center A for Solid Earth Geophysics has developed data bases to further tsunami research. These sets of data include marigrams (tide gage records), a wave-damage slide set, digital source data, descriptive material, and a tsunami wall map. A digital file contains information on methods of tsunami generation, location, and magnitude of generating earthquakes, tsunami size, event validity, and references. The data can be used to describe areas mot likely to generate tsunamis and the locations along shores that experience amplified effects from tsunamis.

  20. Okinawa, Japan

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The southern half of the island of Okinawa, Japan (26.5N, 128.0E) can be seen in this nearly cloud free view. Okinawa is part of the Ryuku Islands which extend from Taiwan northeastward to Kyushu, southernmost of the Japanese Home Islands. The large military base at Kadena, with large runways, is visible near the center of the scene. Kadena is one of several emergency landing sites around the world for the space shuttle.

  1. Volcanic Lightning in Eruptions of Sakurajima Volcano

    NASA Astrophysics Data System (ADS)

    Edens, Harald; Thomas, Ronald; Behnke, Sonja; McNutt, Stephen; Smith, Cassandra; Farrell, Alexandra; Van Eaton, Alexa; Cimarelli, Corrado; Cigala, Valeria; Eack, Ken; Aulich, Graydon; Michel, Christopher; Miki, Daisuke; Iguchi, Masato

    2016-04-01

    In May 2015 a field program was undertaken to study volcanic lightning at the Sakurajima volcano in southern Japan. One of the main goals of the study was to gain a better understanding of small electrical discharges in volcanic eruptions, expanding on our earlier studies of volcanic lightning at Augustine and Redoubt volcanoes in Alaska, USA, and Eyjafjallajökull in Iceland. In typical volcanic eruptions, electrical activity occurs at the onset of an eruption as a near-continual production of VHF emissions at or near to the volcanic vent. These emissions can occur at rates of up to tens of thousands of emissions per second, and are referred to as continuous RF. As the ash cloud expands, small-scale lightning flashes of several hundred meters length begin to occur while the continuous RF ceases. Later on during the eruption larger-scale lightning flashes may occur within the ash cloud that are reminiscent of regular atmospheric lightning. Whereas volcanic lightning flashes are readily observed and reasonably well understood, the nature and morphology of the events producing continuous RF are unknown. During the 2015 field program we deployed a comprehensive set of instrumentation, including a 10-station 3-D Lightning Mapping Array (LMA) that operated in 10 μs high time resolution mode, slow and fast ΔE antennas, a VHF flat-plate antenna operating in the 20-80 MHz band, log-RF waveforms within the 60-66 MHz band, an infra-red video camera, a high-sensitivity Watec video camera, two high-speed video cameras, and still cameras. We give an overview of the Sakurajima field program and present preliminary results using correlated LMA, waveforms, photographs and video recordings of volcanic lightning at Sakurajima volcano.

  2. Heavy atom nitroxyl radicals. I: An ab initio study of the ground and lower electronic excited states of the H2As=O free radical

    NASA Astrophysics Data System (ADS)

    Tarroni, Riccardo; Clouthier, Dennis J.

    2009-09-01

    A series of ab initio calculations have been undertaken to predict the spectroscopic properties of the ground and first two excited states of the recently discovered arsenyl (H2AsO) free radical. This 13 valence electron species can be viewed as similar to the formaldehyde radical anion with a ground state electron configuration of ⋯(π)2(n)2(π∗)1. The arsenyl radical is nonplanar (pyramidal) in the ground state with a 59° out-of-plane angle and a 1.67 Å AsO bond length. It has a low-lying n-π ∗(Ã A2″) excited state (Te˜5000 cm-1) which has a much larger out-of-plane angle (86°) and longer AsO bond length (1.81 Å). The π-π ∗(B˜ A2') excited state at ˜20 500 cm-1 is less pyramidal (out-of-plane angle=70°) and has a somewhat shorter AsO bond (1.77 Å). Similar trends are found for the H2PO and H2NO free radicals, although the latter has a planar ground state, due to sp2 hybridization of the N atom, and a very long B˜ state AsO bond length. The geometric variations of the ground and excited states of the H2EO (E=N, P, As) radicals, as well as the ground states of the corresponding anions and cations, can be readily rationalized from the Walsh diagram of the anion. The variations in the E-O bond length are a result of changes in both the orbital occupancy and pyramidalization of the molecule. The results of the present work have been employed in the analysis of the B˜ A2'-X˜ A2' electronic band system of the H2AsO free radical as reported in the companion paper.

  3. Redetermination of eveite, Mn2AsO4(OH), based on single-crystal X-ray diffraction data

    PubMed Central

    Yang, Yongbo W.; Stevenson, Ryan A.; Siegel, Alesha M.; Downs, Gordon W.

    2011-01-01

    The crystal structure of eveite, ideally Mn2(AsO4)(OH) [dimanganese(II) arsenate(V) hydroxide], was refined from a single crystal selected from a co-type sample from Långban, Filipstad, Varmland, Sweden. Eveite, dimorphic with sarkinite, is structurally analogous with the important rock-forming mineral andalusite, Al2OSiO4, and belongs to the libethenite group. Its structure consists of chains of edge-sharing distorted [MnO4(OH)2] octa­hedra (..2 symmetry) extending parallel to [001]. These chains are cross-linked by isolated AsO4 tetra­hedra (..m symmetry) through corner-sharing, forming channels in which dimers of edge-sharing [MnO4(OH)] trigonal bipyramids (..m symmetry) are located. In contrast to the previous refinement from Weissenberg photographic data [Moore & Smyth (1968 ▶). Am. Mineral. 53, 1841–1845], all non-H atoms were refined with anisotropic displacement param­eters and the H atom was located. The distance of the donor and acceptor O atoms involved in hydrogen bonding is in agreement with Raman spectroscopic data. Examination of the Raman spectra for arsenate minerals in the libethenite group reveals that the position of the peak originating from the O—H stretching vibration shifts to lower wavenumbers from eveite, to adamite, zincolivenite, and olivenite. PMID:22199466

  4. Gaia16aso, Gaia16asq, Gaia16asu and Gaia16atb candidate supernovae near galaxies confirmed by Mercator/Maia imaging

    NASA Astrophysics Data System (ADS)

    Blanco-Cuaresma, S.; Roelens, M.; Semaan, T.; Palaversa, L.; Mowlavi, N.; Eyer, L.

    2016-07-01

    We report confirmation of Gaia Science Alerts transients Gaia16aso, Gaia16asq, Gaia16asu and Gaia16atb. Images were obtained in G and R bands of the Maia instrument mounted to the Flemish 1.2m Mercator telescope at Roque de los Muchachos observatory, La Palma, Canary Islands, Spain, on 2016 July 04 - 05. These new sources are supernovae candidates near galaxies and they are not visible in archival 2MASS and DSS images: Gaia16aso, Gaia16asq, Gaia16asu and Gaia16atb.

  5. Digital Data for Volcano Hazards at Newberry Volcano, Oregon

    USGS Publications Warehouse

    Schilling, S.P.; Doelger, S.; Sherrod, D.R.; Mastin, L.G.; Scott, W.E.

    2008-01-01

    Newberry volcano is a broad shield volcano located in central Oregon, the product of thousands of eruptions, beginning about 600,000 years ago. At least 25 vents on the flanks and summit have been active during the past 10,000 years. The most recent eruption 1,300 years ago produced the Big Obsidian Flow. Thus, the volcano's long history and recent activity indicate that Newberry will erupt in the future. Newberry Crater, a volcanic depression or caldera has been the focus of Newberry's volcanic activity for at least the past 10,000 years. Newberry National Volcanic Monument, which is managed by the U.S. Forest Service, includes the caldera and extends to the Deschutes River. Newberry volcano is quiet. Local earthquake activity (seismicity) has been trifling throughout historic time. Subterranean heat is still present, as indicated by hot springs in the caldera and high temperatures encountered during exploratory drilling for geothermal energy. The report USGS Open-File Report 97-513 (Sherrod and others, 1997) describes the kinds of hazardous geologic events that might occur in the future at Newberry volcano. A hazard-zonation map is included to show the areas that will most likely be affected by renewed eruptions. When Newberry volcano becomes restless, the eruptive scenarios described herein can inform planners, emergency response personnel, and citizens about the kinds and sizes of events to expect. The geographic information system (GIS) volcano hazard data layers used to produce the Newberry volcano hazard map in USGS Open-File Report 97-513 are included in this data set. Scientists at the USGS Cascades Volcano Observatory created a GIS data layer to depict zones subject to the effects of an explosive pyroclastic eruption (tephra fallout, pyroclastic flows, and ballistics), lava flows, volcanic gasses, and lahars/floods in Paulina Creek. A separate GIS data layer depicts drill holes on the flanks of Newberry Volcano that were used to estimate the probability

  6. The evolution of young silicic lavas at Medicine Lake Volcano, California: Implications for the origin of compositional gaps in calc-alkaline series lavas

    USGS Publications Warehouse

    Grove, T.L.; Donnelly-Nolan, J. M.

    1986-01-01

    gap). At Mt. Mazama and Mt. St. Helens, USA and Aso Caldera and Shikotsu, Japan the amphibole-bearing assemblage was important. At Krakatau, Indonesia and Katmai, USA, an augite+orthopyroxene-bearing assemblage was important. In addition to its role in the production of a compositional gap between intermediate and rhyolitic lavas, the crystallization process increases the H2O content of the residual liquid. This rapid increase in residual liquid volatile content which results from the precipitation of a large proportion of crystalline solids may be an important factor among several that lead to explosive silicic eruptions. ?? 1986 Springer-Verlag.

  7. Eruption of Shiveluch Volcano, Kamchatka, Russia

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On the night of June 4, 2001 ASTER captured this thermal image of the erupting Shiveluch volcano. Located on Russia's Kamchatka Peninsula, Shiveluch rises to an altitude of 8028'. The active lava dome complex is seen as a bright (hot) area on the summit of the volcano. To the southwest, a second hot area is either a debris avalanche or hot ash deposit. Trailing to the west is a 25 km ash plume, seen as a cold 'cloud' streaming from the summit. At least 60 large eruptions have occurred during the last 10,000 years; the largest historical eruptions were in 1854 and 1964. Because Kamchatka is located along the major aircraft routes between North America/Europe and the Far East, this area is constantly monitored for potential ash hazards to aircraft. The lower image is the same as the upper, except it has been color coded: red is hot, light greens to dark green are progressively colder, and gray/black are the coldest areas.

    The image is located at 56.7 degrees north latitude, 161.3 degrees east longitude.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in

  8. Remote sensing of Italian volcanos

    NASA Technical Reports Server (NTRS)

    Bianchi, R.; Casacchia, R.; Coradini, A.; Duncan, A. M.; Guest, J. E.; Kahle, A.; Lanciano, P.; Pieri, D. C.; Poscolieri, M.

    1990-01-01

    The results of a July 1986 remote sensing campaign of Italian volcanoes are reviewed. The equipment and techniques used to acquire the data are described and the results obtained for Campi Flegrei and Mount Etna are reviewed and evaluated for their usefulness for the study of active and recently active volcanoes.

  9. New observations at Iwo-Jima caldera, Volcano Islands, Japan

    NASA Astrophysics Data System (ADS)

    Ukawa, U. M.; Fujita, E.; Hill, D.; Kobayashi, T.; Lowenstern, J.; Newhall, C.

    2003-04-01

    Small phreatic eruptions on opposite sides of Iwo-Jima in September and October 2001 marked the beginning of several changes in this largely submarine caldera and trapdoor resurgence of its floor. The northern part of Motoyama, roughly the center of the caldera floor, has risen >120 m in the past 420 years at an average rate of ˜25 cm/y; uplift in the past year has been substantially faster. The main cause of uplift at Iwo-Jima is fresh, episodic(?) magma influx into a reservoir whose top is ˜ 2 km below the caldera floor. Despite roughly 10 million m3/y apparent magma influx, degassing seems to minimize magmatic eruptions.

  10. Infrasound Waveform Classification and Emissions Correlation at Karymsky and Sakurajima Volcanoes

    NASA Astrophysics Data System (ADS)

    Albert, S.; Fee, D.; Lopez, T. M.; Firstov, P. P.; Makhmudov, E.

    2014-12-01

    Infrasound (sound between ~0.01-20 Hz) is often used to monitor volcanoes and provide insight into eruption dynamics. Of the main goals in the volcano infrasound community, associating volcanic emissions with specific infrasound features remains of importance. Here we focus on infrasound collected during two separate field campaigns at Karymsky Volcano, Kamchatka, Russia and Sakurajima Volcano, Japan. Both volcanoes are andesitic and produce frequent eruptions. Recent Karymsky eruptions have been classified into four main eruption types: discrete ash explosions, pulsatory gas emissions, gas jetting, and quiescence followed by an explosion. Sakurajima eruptions are typically ash-rich and are dominantly Vulcanian in character. We use a waveform cross correlation scheme to identify infrasound waveform families from recent eruptions at each volcano. We also identify changes in eruption dynamics by tracking the number and occurrence of these families though time. This can be done on a large scale (changes in relation to the families) as well as on a smaller scale (changes in relation to the subfamilies). During these field campaigns volcanic emissions data were also collected using ground-based sampling, and visual, ultraviolet, and infrared remote sensing techniques. The infrasound waveform families are then correlated with volcanic emissions data to determine unique signatures of volcanic emissions. By comparing model calculations and physical data, this information will hopefully lead to improved monitoring and characterization of volcanic eruptions using infrasound in particular at remote, difficult to monitor volcanoes.

  11. Volcanoes, Central Java, Indonesia

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The island of Java (8.0S, 112.0E), perhaps better than any other, illustrates the volcanic origin of Pacific Island groups. Seen in this single view are at least a dozen once active volcano craters. Alignment of the craters even defines the linear fault line of Java as well as the other some 1500 islands of the Indonesian Archipelago. Deep blue water of the Indian Ocean to the south contrasts to the sediment laden waters of the Java Sea to the north.

  12. Volcanoes of the Solar System

    NASA Astrophysics Data System (ADS)

    Frankel, Charles

    1996-09-01

    Nothing can be more breathtaking than the spectacle of a volcano erupting. Space-age lunar and planetary missions offer us an unprecedented perspective on volcanism. Starting with the Earth, Volcanoes of the Solar System takes the reader on a guided tour of the terrestrial planets and moons and their volcanic features. We see lunar lava fields through the eyes of the Apollo astronauts, and take an imaginary hike up the Martian slopes of Olympus Mons--the tallest volcano in the solar system. Complemented by over 150 photographs, this comprehensive and lucid account of volcanoes describes the most recent data on the unique and varied volcanic features of Venus and updates our knowledge on the prodigiously active volcanoes of Io. A member of the Association of European Volcanologists, Charles Frankel has directed documentary films on geology, astronomy and space exploration and has authored a number of articles on the earth sciences.

  13. Volcanic Activities of Hakkoda Volcano after the 2011 Tohoku Earthquake

    NASA Astrophysics Data System (ADS)

    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. Electronic properties of highly-active Ag3AsO4 photocatalyst and its band gap modulation: an insight from hybrid-density functional calculations.

    PubMed

    Reunchan, Pakpoom; Boonchun, Adisak; Umezawa, Naoto

    2016-08-17

    The electronic structures of highly active Ag-based oxide photocatalysts Ag3AsO4 and Ag3PO4 are studied by hybrid-density functional calculations. It is revealed that Ag3AsO4 and Ag3PO4 are indirect band gap semiconductors. The Hartree-Fock mixing parameters are fitted for experimental band gaps of Ag3AsO4 (1.88 eV) and Ag3PO4 (2.43 eV). The smaller electron effective mass and the lower valence band edge of Ag3AsO4 are likely to be responsible for the superior photocatalytic oxidation reaction to Ag3PO4. The comparable lattice constant and analogous crystal structure between the two materials allow the opportunities of fine-tuning the band gap of Ag3AsxP1-xO4 using a solid-solution approach. The development of Ag3AsxP1-xO4 should be promising for the discovery of novel visible-light sensitized photocatalysts. PMID:27502998

  15. Coordination of Advanced Solar Observatory (ASO) Science Working Group (SWG) for the study of instrument accommodation and operational requirements on space station

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1989-01-01

    The objectives are to coordinate the activities of the Science Working Group (SWG) of the Advanced Solar Observatory (ASO) for the study of instruments accommodation and operation requirements on board space station. In order to facilitate the progress of the objective, two conferences were organized, together with two small group discussions.

  16. Elysium Mons Volcano

    NASA Technical Reports Server (NTRS)

    1998-01-01

    On July 4, 1998--the first anniversary of the Mars Pathfinder landing--Mars Global Surveyor's latest images were radioed to Earth with little fanfare. The images received on July 4, 1998, however, were very exciting because they included a rare crossing of the summit caldera of a major martian volcano. Elysium Mons is located at 25oN, 213oW, in the martian eastern hemisphere. Elysium Mons is one of three large volcanoes that occur on the Elysium Rise-- the others are Hecates Tholus (northeast of Elysium Mons) and Albor Tholus (southeast of Elysium Mons). The volcano rises about 12.5 kilometers (7.8 miles) above the surrounding plain, or about 16 kilometers (9.9 miles) above the martian datum-- the 'zero' elevation defined by average martian atmospheric pressure and the planet's radius.

    Elysium Mons was discovered by Mariner 9 in 1972. It differs in a number of ways from the familiar Olympus Mons and other large volcanoes in the Tharsis region. In particular, there are no obvious lava flows visible on the volcano's flanks. The lack of lava flows was apparent from the Mariner 9 images, but the new MOC high resolution image--obtained at 5.24 meters (17.2 feet) per pixel--illustrates that this is true even when viewed at higher spatial resolution.

    Elysium Mons has many craters on its surface. Some of these probably formed by meteor impact, but many show no ejecta pattern characteristic of meteor impact. Some of the craters are aligned in linear patterns that are radial to the summit caldera--these most likely formed by collapse as lava was withdrawn from beneath the surface, rather than by meteor impact. Other craters may have formed by explosive volcanism. Evidence for explosive volcanism on Mars has been very difficult to identify from previous Mars spacecraft images. This and other MOC data are being examined closely to better understand the nature and origin of volcanic features on Mars.

    The three MOC images, 40301 (red wide angle), 40302 (blue wide angle

  17. Li3Al(MoO2)2O2(AsO4)2

    PubMed Central

    Hajji, Mounir; Zid, Mohamed Faouzi; Driss, Ahmed

    2009-01-01

    Single crystals of trilithium(I) aluminium(III) bis­[dioxidomolybdenum(VI)] dioxide bis­[arsenate(V)], Li3AlMo2As2O14, have been prepared by solid-state reaction at 788 K. The structure consists of AsO4 tetra­hedra, AlO6 octa­hedra and Mo2O10 groups sharing corners to form a three-dimensional framework containing channels running respectively along the [100] and [010] directions, where the Li+ ions are located. This structure is compared with compounds having (MX 2O12)n chains (M = Mo, Al and X = P, As) and others containing M 2O10 (M = Mo, Fe) dimers. PMID:21582037

  18. Mount Rainier active cascade volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

  19. Eruptive viscosity and volcano morphology

    NASA Technical Reports Server (NTRS)

    Posin, Seth B.; Greeley, Ronald

    1988-01-01

    Terrestrial central volcanoes formed predominantly from lava flows were classified as shields, stratovolcanoes, and domes. Shield volcanoes tend to be large in areal extent, have convex slopes, and are characterized by their resemblance to inverted hellenic war shields. Stratovolcanoes have concave slopes, whereas domes are smaller and have gentle convex slopes near the vent that increase near the perimeter. In addition to these differences in morphology, several other variations were observed. The most important is composition: shield volcanoes tend to be basaltic, stratovolcanoes tend to be andesitic, and domes tend to be dacitic. However, important exceptions include Fuji, Pico, Mayon, Izalco, and Fuego which have stratovolcano morphologies but are composed of basaltic lavas. Similarly, Ribkwo is a Kenyan shield volcano composed of trachyte and Suswa and Kilombe are shields composed of phonolite. These exceptions indicate that eruptive conditions, rather than composition, may be the primary factors that determine volcano morphology. The objective of this study is to determine the relationships, if any, between eruptive conditions (viscosity, erupted volume, and effusion rate) and effusive volcano morphology. Moreover, it is the goal of this study to incorporate these relationships into a model to predict the eruptive conditions of extraterrestrial (Martian) volcanoes based on their morphology.

  20. Volcano spacing and plate rigidity

    SciTech Connect

    Brink, U. )

    1991-04-01

    In-plane stresses, which accompany the flexural deformation of the lithosphere under the load adjacent volcanoes, may govern the spacing of volcanoes in hotspot provinces. Specifically, compressive stresses in the vicinity of a volcano prevent new upwelling in this area, forcing a new volcano to develop at a minimum distance that is equal to the distance in which the radial stresses change from compressional to tensile (the inflection point). If a volcano is modeled as a point load on a thin elastic plate, then the distance to the inflection point is proportional to the thickness of the plate to the power of 3/4. Compilation of volcano spacing in seven volcanic groups in East Africa and seven volcanic groups of oceanic hotspots shows significant correlation with the elastic thickness of the plate and matches the calculated distance to the inflection point. In contrast, volcano spacing in island arcs and over subduction zones is fairly uniform and is much larger than predicted by the distance to the inflection point, reflecting differences in the geometry of the source and the upwelling areas.

  1. The mixed anion mineral parnauite Cu 9[(OH) 10|SO 4|(AsO 4) 2]·7H 2O—A Raman spectroscopic study

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Keeffe, Eloise C.

    2011-10-01

    The mixed anion mineral parnauite Cu 9[(OH) 10|SO 4|(AsO 4) 2]·7H 2O from two localities namely Cap Garonne Mine, Le Pradet, France and Majuba Hill mine, Pershing County, Nevada, USA has been studied by Raman spectroscopy. The Raman spectrum of the French sample is dominated by an intense band at 975 cm -1 assigned to the ν1 (SO 4) 2- symmetric stretching mode and Raman bands at 1077 and 1097 cm -1 may be attributed to the ν3 (SO 4) 2- antisymmetric stretching mode. Two Raman bands 1107 and 1126 cm -1 are assigned to carbonate CO 32- symmetric stretching bands and confirms the presence of carbonate in the structure of parnauite. The comparatively sharp band for the Pershing County mineral at 976 cm -1 is assigned to the ν1 (SO 4) 2- symmetric stretching mode and a broad spectral profile centered upon 1097 cm -1 is attributed to the ν3 (SO 4) 2- antisymmetric stretching mode. Two intense bands for the Pershing County mineral at 851 and 810 cm -1 are assigned to the ν1 (AsO 4) 3- symmetric stretching and ν3 (AsO 4) 3- antisymmetric stretching modes. Two Raman bands for the French mineral observed at 725 and 777 cm -1 are attributed to the ν3 (AsO 4) 3- antisymmetric stretching mode. For the French mineral, a low intensity Raman band is observed at 869 cm -1 and is assigned to the ν1 (AsO 4) 3- symmetric stretching vibration. Chemical composition of parnauite remains open and the question may be raised is parnauite a solid solution of two or more minerals such as a copper hydroxy-arsenate and a copper hydroxy sulphate.

  2. Counterfactual Volcano Hazard Analysis

    NASA Astrophysics Data System (ADS)

    Woo, Gordon

    2013-04-01

    , if a major storm surge happens to arrive at a high astronomical tide, sea walls may be overtopped and flooding may ensue. In the domain of geological hazards, periods of volcanic unrest may generate precursory signals suggestive of imminent volcanic danger, but without leading to an actual eruption. Near-miss unrest periods provide vital evidence for assessing the dynamics of volcanoes close to eruption. Where the volcano catalogue has been diligently revised to include the maximum amount of information on the phenomenology of unrest periods, dynamic modelling and hazard assessment may be significantly refined. This is illustrated with some topical volcano hazard examples, including Montserrat and Santorini.

  3. Source Inversions of Volcano Infrasound: Mass Outflux and Force System for Transient Explosive Eruptions

    NASA Astrophysics Data System (ADS)

    Kim, K.; Fee, D.; Lees, J. M.; Yokoo, A.; Ruiz, M. C.

    2014-12-01

    Sources of volcano infrasound associated with explosive eruptions are typically modeled assuming an acoustic monopole and/or dipole. While the monopole represents the mass outflux of erupted materials, the dipole represents a force system acting in the source region during eruptions. Therefore, appropriate acoustic source inversions of volcano infrasound data can provide estimates of eruption parameters which are critical to understanding eruption dynamics. Reliability of the source parameters is dominantly controlled by the accuracy of the acoustic Green's functions between the source and receiver positions. Conventional source inversions of volcano infrasound, however, were typically performed using a simplified Green's function obtained in a free space or half space. This may result in intolerable errors in the source parameters, especially when the infrasound waveforms are significantly distorted by volcano topography and/or local atmospheric variability (i.e., layered velocity structure or wind). In this study we present a full waveform inversion technique for volcano infrasound using numerical Green's functions. A full 3-D Finite-Difference Time-Domain (FDTD) method accelerated with GPU is used to compute accurate Green's functions taking into account volcano topography and local atmospheric conditions. The presented method is applied to data recorded at Sakurajima volcano (Japan) and Tungurahua volcano (Ecuador), which provide a large volume of high-quality data recorded by azimuthally well-distributed stations within 2 -- 6 km distance of the volcanoes. We analyze infrasound signals associated with explosive eruptions exhibiting 1) distinct explosion waveforms followed by gas discharges and 2) strong anisotropic radiation patterns, which can be caused by either source directivity or topographic barriers/reflections. Here the role of topography in controlling the infrasound radiation is investigated through numerical modeling, and then the observed

  4. Mt. Fuji, Japan

    NASA Technical Reports Server (NTRS)

    2001-01-01

    [figure removed for brevity, see original site] Click on image to view the movie

    The nearly perfectly conical profile of Fuji soars 3,776 meters (12,388 feet) above sea level on southern Honshu, near Tokyo. The highest mountain in Japan, Fuji is the country's most familiar symbol. The summit of this graceful, dormant volcano is broken by a crater 610 meters (2,000 feet) in diameter. The crater is ringed by eight jagged peaks. The five Fuji Lakes lie on the northern slopes of the mountain, all formed in the wake of lava flows. Mirrored in the still waters of Kawaguchi-ko, the most beautiful of the five lakes, is a reflection of Fuji. Part of Fuji-Hakone-Izu National Park, Fuji last erupted for a two-month period starting in November 1707, covering Tokyo, some 100 kilometers (60 miles) away, with a layer of ash. According to legend, Fuji arose from the plain during a single night in 286 BC. Geologically, the mountain is much older than this.

    Considered sacred by many, Fuji is surrounded by temples and shrines. Thousands of pilgrims climb the mountain each year as part of their religious practice, hoping to reach the summit by dawn to watch the sunrise. This animated fly-by was created by draping visible and near infrared image data over a digital topography model, created from ASTER's stereo bands. The spatial resolution of both the image and topography is 15 m. The image is centered at 35.3 degrees north latitude, 138.7 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  5. Monitoring active volcanoes

    USGS Publications Warehouse

    Tilling, Robert I.

    1987-01-01

    One of the most spectacular, awesomely beautiful, and at times destructive displays of natural energy is an erupting volcano, belching fume and ash thousands of meters into the atmosphere and pouring out red-hot molten lava in fountains and streams. Countless eruptions in the geologic past have produced volcanic rocks that form much of the Earth's present surface. The gradual disintegration and weathering of these rocks have yielded some of the richest farmlands in the world, and these fertile soils play a significant role in sustaining our large and growing population. Were it not for volcanic activity, the Hawaiian Islands with their sugar cane and pineapple fields and magnificent landscapes and seascapes would not exist to support their residents and to charm their visitors. Yet, the actual eruptive processes are catastrophic and can claim life and property.

  6. Active submarine volcano sampled

    USGS Publications Warehouse

    Taylor, B.

    1983-01-01

    On June 4, 1982, two full dredge hauls of fresh lava were recovered from the upper flanks of Kavachi submarine volcano, Solomon Islands, in the western Pacific Ocean, from the water depths of 1,200 and 2,700 feet. the shallower dredge site was within 0.5 mile of the active submarine vent shown at the surface by an area of slick water, probably caused by gas emissions. Kavachi is a composite stratovolcano that has been observed to erupt every year or two for at least the last 30 years (see photographs). An island formed in 1952, 1961, 1965, and 1978; but, in each case, it rapidly eroded below sea level. The latest eruption was observed by Solair pilots during the several weeks up to and including May 18, 1982. 

  7. Volcanoes, Third Edition

    NASA Astrophysics Data System (ADS)

    Nye, Christopher J.

    It takes confidence to title a smallish book merely “Volcanoes” because of the impliction that the myriad facets of volcanism—chemistry, physics, geology, meteorology, hazard mitigation, and more—have been identified and addressed to some nontrivial level of detail. Robert and Barbara Decker have visited these different facets seamlessly in Volcanoes, Third Edition. The seamlessness comes from a broad overarching, interdisciplinary, professional understanding of volcanism combined with an exceptionally smooth translation of scientific jargon into plain language.The result is a book which will be informative to a very broad audience, from reasonably educated nongeologists (my mother loves it) to geology undergraduates through professional volcanologists. I bet that even the most senior professional volcanologists will learn at least a few things from this book and will find at least a few provocative discussions of subjects they know.

  8. HSDP: The Lost Volcano

    NASA Astrophysics Data System (ADS)

    Blichert-Toft, J.; Albarede, F.

    2008-12-01

    We measured high-precision Hf, Nd, and Pb isotope compositions for 40 samples from the final leg of the Hawaii Scientific Drilling Project (HSDP) core using solution chemistry and MC-ICP-MS. This final leg extends the drill core from 3097.7 mbsl down to a depth of 3505.7 mbsl. The new isotope data are indistinguishable from those higher up in the Mauna Kea part of the core and vary from, respectively, +11.6 to +12.3, +6.4 to +7.0, and 18.2948 to 18.6819 for ɛHf, ɛNd, and 206Pb/204Pb. The Pb isotope data define three linear trends with a common intersection. Principal component analysis recognizes no more than three geochemical end-members (99.8% of the variance) among these trends. When all the Pb isotope data acquired so far ([1-3] and this work) are pooled, two contrasting groups stand out, mostly with respect to 208Pb/206Pb. (1) A first coherent, prevalent group is identified, which represents the Kea main eruptive sequence. This group combines the Kea-mid8 and the Kea-lo8 subgroups of [3]: although these subgroups define two separate trends in Pb-Pb isotope space, they smoothly follow each other in time. (2) A second group of 15 flows at depths below 2000 mbsl is characterized by distinctly higher source Th/U and, for the samples above the new core samples, also high 3He/4He. These samples belong to the K/L group of [2] and to the Kea-hi8 group of [3] and are about 0.4 (Hf) and 0.5 (Nd) ɛ units below the main sequence Kea values. The toggle between these two groups of flows is so sharp and repetitive and the gap between the values so conspicuous that the alternation must reflect eruptions from distinct volcanic centers, Mauna Kea and an unknown volcano (K/L) that bears some isotopic resemblance to Kilauea for Nd and Hf and to Loihi for He [2, 4]. This 'lost' volcano stopped erupting about 550 ka ago, i.e., 200 ka before the oldest ages known for Kilauea [5], and is presently buried under 2-3000 m of Mauna Kea flows. We left out the data on the lost volcano

  9. Living with volcanoes

    USGS Publications Warehouse

    Wright, Thomas L.; Pierson, Thomas C.

    1992-01-01

    The 1980 cataclysmic eruption of Mount St. Helens (Lipman and Mullineaux, 1981) in southwestern Washington ushered in a decade marked by more worldwide volcanic disasters and crises than any other in recorded history. Volcanoes killed more people (over 28,500) in the 1980's than during the 78 years following 1902 eruption of Mount Pelee (Martinique). Not surprisingly, volcanic phenomena and attendant hazards received attention from government authorities, the news media, and the general public. As part of this enhanced global awareness of volcanic hazards, the U.S. Geological Survey (Bailey and others, 1983) in response to the eruptions or volcanic unrest during the 1980's at Mount St. Helens and Redoubt are still erupting intermittently, and the caldera unrest at Long Valley also continues, albeit less energetically than during the early 1980's.

  10. Flank tectonics of Martian volcanoes

    NASA Technical Reports Server (NTRS)

    Thomas, Paul J.; Squyres, Steven W.; Carr, Michael H.

    1990-01-01

    The origin of the numerous terraces on the flanks of the Olympus Mons volcano on Mars, seen on space images to be arranged in a roughly concentric pattern, is investigated. The images of the volcano show that the base of each terrace is marked by a modest but abrupt change in slope, suggesting that these terraces could be thrust faults caused by a compressional failure of the cone. The mechanism of faulting and the possible effect of the interior structure of Olympus Mons was investigated using a numerical model for elastic stresses within a Martian volcano, constructed for that purpose. Results of the analysis supports the view that the terraces on Olympus Mons, as well as on other three Martian volcanoes, including Ascraeus Mons, Arsia Mons, and Pavonis Mons are indeed thrust faults.

  11. Morphometric evolution of composite volcanoes

    NASA Technical Reports Server (NTRS)

    Wood, C. A.

    1978-01-01

    Statistical relations between geometry, slope, and age for 26 circum-Pacific composite volcanoes (stratovolcanoes) are presented. Topics considered include morphometry, eruption characteristics, growth rates, repose periods, flow lengths, and petrological/chemical trends. Composite and cinder cones are compared, and it is suggested that, if cinder cones do evolve into composite volcanoes, a fundamental change in cone morphometry, eruption style, and petrology occurs at a basal diameter of 2 km.

  12. Mahukona: The missing Hawaiian volcano

    SciTech Connect

    Garcia, M.O.; Muenow, D.W. ); Kurz, M.D. )

    1990-11-01

    New bathymetric and geochemical data indicate that a seamount west of the island of Hawaii, Mahukona, is a Hawaiian shield volcano. Mahukona has weakly alkalic lavas that are geochemically distinct. They have high {sup 3}He/{sup 4}He ratios (12-21 times atmosphere), and high H{sub 2}O and Cl contents, which are indicative of the early state of development of Hawaiian volcanoes. The He and Sr isotopic values for Mahukona lavas are intermediate between those for lavas from Loihi and Manuna Loa volcanoes and may be indicative of a temporal evolution of Hawaiian magmas. Mahukona volcano became extinct at about 500 ka, perhaps before reaching sea level. It fills the previously assumed gap in the parallel chains of volcanoes forming the southern segment of the Hawaiian hotspot chain. The paired sequence of volcanoes was probably caused by the bifurcation of the Hawaiian mantle plume during its ascent, creating two primary areas of melting 30 to 40 km apart that have persisted for at least the past 4 m.y.

  13. Mount St. Helens and Kilauea volcanoes

    SciTech Connect

    Barrat, J. )

    1989-01-01

    Mount St. Helens' eruption has taught geologists invaluable lessons about how volcanoes work. Such information will be crucial in saving lives and property when other dormant volcanoes in the northwestern United States--and around the world--reawaken, as geologists predict they someday will. Since 1912, scientists at the U.S. Geological Survey's Hawaiian Volcano Observatory have pioneered the study of volcanoes through work on Mauna Loa and Kilauea volcanoes on the island of Hawaii. In Vancouver, Wash., scientists at the Survey's Cascades Volcano Observatory are studying the after-effects of Mount St. Helens' catalysmic eruption as well as monitoring a number of other now-dormant volcanoes in the western United States. This paper briefly reviews the similarities and differences between the Hawaiian and Washington volcanoes and what these volcanoes are teaching the volcanologists.

  14. Local deformations around volcanoes associated with the 2011 off the Pacific coast of Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Ozawa, T.; Fujita, E.

    2013-01-01

    An Mw 9.0 great earthquake struck northeast Japan on 11 March 2011, causing crustal deformation of 1 to 2 m in volcanic areas. We applied synthetic aperture radar interferometry using Phased Array type L-band Synthetic Aperture Radar on the ALOS satellite to investigate local deformation around volcanoes associated with the earthquake. We estimated the fault-slip distribution along the trough based on obtained interferograms and crustal deformation from GEONET, and the estimated fault model explained the observed coseismic deformations well. The residual suggested local deformation around the Akita-Komagatake, Kurikoma, Zao, Azuma, and Nasu volcanoes. Their deformations were obtained from independent synthetic aperture radar pairs. Additionally, deformations in the Kurikoma, Zao, and Azuma volcanoes were confirmed by GEONET data (no GEONET stations are located in the deformation areas of other volcanoes). These facts indicate that the obtained local deformations must be actual deformations, rather than noise. Our hypothesis is that coseismic extensional deformation concentrates in the soft medium under a volcano (e.g., magma and its surrounding rock) and that this deformation has caused local deformation with subsidence. To validate this hypothesis, we carried out numerical experiments using the finite element method for a soft medium under a volcano. Distributions of observed local deformations stretch in the direction of the minor principal axis of strain, and such distributions were obtained in this experiment, indicating that the hypothesis is plausible. Conceivably, such a concentration of coseismic deformation in a magma chamber may induce a volcanic eruption.

  15. Vertical Motions of Oceanic Volcanoes

    NASA Astrophysics Data System (ADS)

    Clague, D. A.; Moore, J. G.

    2006-12-01

    Oceanic volcanoes offer abundant evidence of changes in their elevations through time. Their large-scale motions begin with a period of rapid subsidence lasting hundreds of thousands of years caused by isostatic compensation of the added mass of the volcano on the ocean lithosphere. The response is within thousands of years and lasts as long as the active volcano keeps adding mass on the ocean floor. Downward flexure caused by volcanic loading creates troughs around the growing volcanoes that eventually fill with sediment. Seismic surveys show that the overall depression of the old ocean floor beneath Hawaiian volcanoes such as Mauna Loa is about 10 km. This gross subsidence means that the drowned shorelines only record a small part of the total subsidence the islands experienced. In Hawaii, this history is recorded by long-term tide-gauge data, the depth in drill holes of subaerial lava flows and soil horizons, former shorelines presently located below sea level. Offshore Hawaii, a series of at least 7 drowned reefs and terraces record subsidence of about 1325 m during the last half million years. Older sequences of drowned reefs and terraces define the early rapid phase of subsidence of Maui, Molokai, Lanai, Oahu, Kauai, and Niihau. Volcanic islands, such as Maui, tip down toward the next younger volcano as it begins rapid growth and subsidence. Such tipping results in drowned reefs on Haleakala as deep as 2400 m where they are tipped towards Hawaii. Flat-topped volcanoes on submarine rift zones also record this tipping towards the next younger volcano. This early rapid subsidence phase is followed by a period of slow subsidence lasting for millions of years caused by thermal contraction of the aging ocean lithosphere beneath the volcano. The well-known evolution along the Hawaiian chain from high to low volcanic island, to coral island, and to guyot is due to this process. This history of rapid and then slow subsidence is interrupted by a period of minor uplift

  16. Development and utilization of geothermal energy in Japan

    SciTech Connect

    Nakamura, H.

    1981-10-01

    Japan has about 10% of all active volcanoes in the world. In 1966, Azuma Kako Co., Ltd. (present Japan Metals and Chemicals Co., Ltd.) constructed Japan's first geothermal power plant of 20 MW. Since 1966, several geothermal power plants have been constructed in Kyushu and Northeast Japan. At present there exist six power plants amounting to 162 MW in total. One more power plant is now under construction in Hokkaido, expected to begin operation in fall 1982. All six geothermal power plants are located in national parks. Two of them are expected to be doubled in near future. Now the developers, amounting to about ten, are implementing their surveys mainly outside the parks, and it is forecast that in 1985 400 MW and in 1990 1400 MW power will be obtained by geothermal energy.

  17. Sand Volcano Following Earthquake

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Sand boil or sand volcano measuring 2 m (6.6 ft.) in length erupted in median of Interstate Highway 80 west of the Bay Bridge toll plaza when ground shaking transformed loose water-saturated deposit of subsurface sand into a sand-water slurry (liquefaction) in the October 17, 1989, Loma Prieta earthquake. Vented sand contains marine-shell fragments. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: J.C. Tinsley, U.S. Geological Survey)

  18. Satellite monitoring of African volcanoes by means of RSTVOLC

    NASA Astrophysics Data System (ADS)

    Pergola, Nicola; Coviello, Irina; Falconieri, Alfredo; Filizzola, Carolina; Lacava, Teodosio; Liuzzi, Mariangela; Marchese, Francesco; Paciello, Rossana; Tramutoli, Valerio

    2015-04-01

    RSTVOLC is an algorithm for volcanic hot spot detection from space based on the Robust Satellite Techniques (RST) multi-temporal approach. This algorithm was firstly tested on Mt. Etna area, analyzing a long-term time series of infrared Advanced Very High Resolution Radiometer (AVHRR) satellite records, and was then implemented on data provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) to study a number of volcanoes in different geographic areas, including Asamayama (Japan) and Eyjafjallajökull (Iceland). Recently, RSTVOLC has been exported on data provided by geostationary sensors such as the Spinning Enhanced Visible and Infrared Imager (SEVIRI), onboard Meteosat Second Generation (MSG) satellites, allowing for the timely detection and real time monitoring of thermal volcanic phenomena. In this work, recent results achieved studying some important African volcanoes by means of polar and geostationary satellite data are presented. Outcomes and results achieved by RSTVOLC studying some past Ol Donyo Lengai (Tanzania) eruptions and the recent Nyamuragira (Congo) activity are reported and discussed, also for comparison with other independent hot spot detection techniques. This study confirms that RSTVOLC may be successfully used to monitor volcanoes at a global scale and to detect low level thermal activities, thanks to its intrinsic self-adaptivity to different observational/environmental conditions as well as to its high sensitivity to sublte hot spots, contributing to volcanic risk mitigation.

  19. Three-dimensional seismic attenuation structure beneath Kyusyu, Japan: Implications for arc magmatism

    NASA Astrophysics Data System (ADS)

    Saita, H.; Nakajima, J.; Shiina, T.

    2014-12-01

    The Philippine Sea (PHS) plate is subducting beneath Kyusyu and a clear volcanic front is formed through the middle of the arc. However, there is a volcanic gap in the central part of Kyushu, between Aso and Kirishima volcanoes. Many studies have discussed arc magmatism in Kyushu in terms of 3D seismic velocity structure, but little is known on seismic attenuation structure. Seismic attenuation structure provides additional insights into subduction-zone dynamics, because higher-temperature environments or the existence of fluids may have different effects on seismic attenuation from on seismic velocity. Therefore the estimate of seismic attenuation is very important to understand arc magmatism and mantle dynamics in subduction zone. This study estimates seismic attenuation structure beneath Kyushu using a large number of high-quality waveform data. We applied the method of Nakajima et al. (2013, JGR) to waveform data derived from 3052 earthquakes that occurred from April 2003 to May 2014. We determined the corner frequency of earthquakes by the spectral ratio method of S-coda waves. Then, we determined a whole-path attenuation term (t*), site-amplification factors and spectrum level simultaneously by a joint inversion. Finally, the t* values (N= 62290) were inverted to obtain three-dimensional attenuation structure. The obtained results show several interesting features. First, the subducting PHS slab is imaged as a low attenuation zone. Second, high-attenuation zone exists in the fore-arc mantle. This high-attenuation zone corresponds spatially to a high Poisson's ratio area, suggesting that the mantle is serpentinized as a result of fluids released by dehydration in the subducting crust. Third, an inclined high-attenuation zone that is interpreted as a mantle upwelling flow is observed in the back-arc mantle. However, the inclined high-attenuation zone is less developed in the volcanic gap between Aso and Kirishima volcanoes. This observation suggests the

  20. The molecular structure of the multianion mineral hidalgoite PbAl 3(AsO 4)(SO 4)(OH) 6 - Implications for arsenic removal from soils

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Palmer, Sara J.; Xi, Yunfei

    2011-11-01

    The objective of this research is to determine the molecular structure of the mineral hidalgoite PbAl 3(AsO 4)(SO 4)(OH) 6 using vibrational spectroscopy. The mineral is found in old mine sites. Observed bands are assigned to the stretching and bending vibrations of (SO 4) 2- and (AsO 4) 3- units, stretching and bending vibrations of hydrogen bonded (OH) - ions and Al 3+-(O,OH) units. The approximate range of O-H⋯O hydrogen bond lengths is inferred from the Raman and infrared spectra. Values of 2.6989 Å, 2.7682 Å, 2.8659 Å were obtained. The formation of hidalgoite may offer a mechanism for the removal of arsenic from the environment.

  1. A new method for As(V) removal from waters by precipitation of mimetite Pb5(AsO4)3Cl on Pb-activated zeolite

    NASA Astrophysics Data System (ADS)

    Manecki, Maciej; Buszkiewicz, Urszula

    2016-04-01

    A new method for removal of arsenate AsO43‑ ions from aqueous solutions is proposed. The principle of the method stems from precipitation of very insoluble crystalline lead arsenate apatite (mimetite Pb5(AsO4)3Cl) induced by bringing in contact Pb-activated zeolite and As-contaminated water in the presence of Cl‑. Zeolite is activated by sorption of Pb2+ followed by washing with water to remove the excess of Pb and to desorbe weakly adsorbed ions. Lead adsorbed on zeolite is bound strong enough to prevent desorption by water but weak enough to undergo desorption induced by heterogeneous precipitation of mimetite nanocrystals on the surface of zeolite. The experiment consisted of two steps. In the first step, aliquots of 0.5 g of natural clinoptilolite zeolite (from Zeocem a.s., Bystré, Slovak Republic) were reacted with 40 mL of solutions containing 20, 100, 500, and 2000 mg Pb/L (pH =4.5; reaction for 30 minutes followed by centrifugation). The amount of Pb sorbed was calculated from the drop of Pb concentration in solution. Centrifuged zeolite was washed three times by mixing with 10 mL of DDI water, followed by centrifugation. No Pb was detected in the water after second washing. Wet pulp resulting from this stage was exposed to solutions containing 70 mg/L Cl‑ and various concentrations of AsO43‑ (2 and 100 mg As/L; pH=4). Complete removal of As was observed for 2 mg As/L solutions mixed with zeolite-20 and zeolite-100. The precipitation of mimetite Pb5(AsO4)3Cl in the form of hexagonal crystals ca. 0.25 μm in size was observed using SEM/EDS. This work is partially funded by AGH research grant no 11.11.140.319.

  2. Be(3)(AsO4)2. 2H2O, a new berylloarsenate phase containing bridged tetrahedral 3-rings. Technical report, 1 June 1992-31 May 1993

    SciTech Connect

    Harrison, W.T.; Nenoff, T.M.; Gier, T.E.; Stucky, G.D.

    1993-02-15

    The high-temperature/high-pressure hydrothermal synthesis and X-ray single crystal structure of Be3(AsO4)2(dot)2H2O is described: the title compound contains a three-dimensional network of BeO4 and AsO4 tetrahedra. The structural motif includes infinite layers of bridged tetrahedral 3- and 4-rings. 9Be MAS NMR data are consistent with the Be-atom environments in the crystal structure.

  3. Lifespans of Cascade Arc volcanoes

    NASA Astrophysics Data System (ADS)

    Calvert, A. T.

    2015-12-01

    Compiled argon ages reveal inception, eruptive episodes, ages, and durations of Cascade stratovolcanoes and their ancestral predecessors. Geologic mapping and geochronology show that most Cascade volcanoes grew episodically on multiple scales with periods of elevated behavior lasting hundreds of years to ca. 100 kyr. Notable examples include the paleomag-constrained, few-hundred-year-long building of the entire 15-20 km3 Shastina edifice at Mt. Shasta, the 100 kyr-long episode that produced half of Mt. Rainier's output, and the 30 kyr-long episode responsible for all of South and Middle Sister. Despite significant differences in timing and rates of construction, total durations of active and ancestral volcanoes at discrete central-vent locations are similar. Glacier Peak, Mt. Rainier, Mt. Adams, Mt. Hood, and Mt. Mazama all have inception ages of 400-600 ka. Mt. St. Helens, Mt. Jefferson, Newberry Volcano, Mt. Shasta and Lassen Domefield have more recent inception ages of 200-300 ka. Only the Sisters cluster and Mt. Baker have established eruptive histories spanning less than 50 kyr. Ancestral volcanoes centered 5-20 km from active stratocones appear to have similar total durations (200-600 kyr), but are less well exposed and dated. The underlying mechanisms governing volcano lifecycles are cryptic, presumably involving tectonic and plumbing changes and perhaps circulation cycles in the mantle wedge, but are remarkably consistent along the arc.

  4. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Eyjafjallajökull Volcano Ash Plume Particle Properties     ... satellite flew over Iceland's erupting Eyjafjallajökull volcano on April 19, 2010, its Multi-angle Imaging SpectroRadiometer (MISR) ...

  5. Earthquakes & Volcanoes, Volume 23, Number 6, 1992

    USGS Publications Warehouse

    U.S. Geological Survey; Gordon, David W., (Edited By)

    1993-01-01

    Earthquakes and Volcanoes is published bimonthly by the U.S. Geological Survey to provide current information on earthquakes and seismology, volcanoes, and related natural hazards of interest to both generalized and specialized readers.

  6. The synthesis and characterization of 1 1 1 1 type diluted ferromagnetic semiconductor (La1-x Ca x )(Zn1-x Mn x )AsO

    NASA Astrophysics Data System (ADS)

    Ding, Cui; Guo, Shengli; Zhao, Yao; Man, Huiyuan; Fu, Licheng; Gu, Yilun; Wang, Zhouyang; Liu, L.; Frandsen, B. A.; Cheung, S.; Uemura, Y. J.; Goko, T.; Luetkens, H.; Morenzoni, E.; Zhao, Yang; Ning, F. L.

    2016-01-01

    We report the synthesis and characterization of a bulk form diluted magnetic semiconductor, (La1-x Ca x )(Zn1-y Mn y )AsO, with a layered crystal structure isostructural to that of the 1 1 1 1 type Fe-based high-temperature superconductor LaFeAsO and the antiferromagnetic LaMnAsO. With Ca and Mn codoping into LaZnAsO, the ferromagnetic ordering occurs below the Curie temperature {{T}\\text{C}}   ˜30 K. Taking advantage of the decoupled charge and spin doping, we investigate the influence of carrier concentration on the ferromagnetic ordering state. For a fixed Mn concentration of 10%, {{T}\\text{C}} increases from 24 K to 30 K when the Ca concentration increases from 5% to 10%. Further increase of Ca concentration reduces both the coercive field and saturation moment. Muon spin relaxation measurements confirm the ferromagnetically ordered state, and clearly demonstrate that (La1-x Ca x )(Zn1-y Mn y )AsO shares a common mechanism for the ferromagnetic exchange interaction with (Ga,Mn)As. Neutron scattering measurements show no structural transition in (La0.90Ca0.10)(Zn0.90Mn0.10)AsO below 300 K.

  7. Raman spectroscopy of the multi-anion mineral schlossmacherite (H 3O,Ca)Al 3(AsO 4,PO 4,SO 4) 2(OH) 6

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Palmer, Sara J.; Xi, Yunfei

    2012-02-01

    The mineral schlossmacherite (H 3O,Ca)Al 3(AsO 4,PO 4,SO 4) 2(OH) 6, a multi-cation-multi-anion mineral of the beudantite mineral subgroup has been characterised by Raman spectroscopy. The mineral and related minerals functions as a heavy metal collector and is often amorphous or poorly crystalline, such that XRD identification is difficult. The Raman spectra are dominated by an intense band at 864 cm -1, assigned to the symmetric stretching mode of the AsO 43- anion. Raman bands at 809 and 819 cm -1 are assigned to the antisymmetric stretching mode of AsO 43-. The sulphate anion is characterised by bands at 1000 cm -1 ( ν1), and at 1031, 1082 and 1139 cm -1 ( ν3). Two sets of bands in the OH stretching region are observed: firstly between 2800 and 3000 cm -1 with bands observed at 2850, 2868, 2918 cm -1 and secondly between 3300 and 3600 with bands observed at 3363, 3382, 3410, 3449 and 3537 cm -1. These bands enabled the calculation of hydrogen bond distances and show a wide range of H-bond distances.

  8. Synthesis and Characterization of Bismuth Magnesium Phosphate and Arsenate: BiMg 2PO 6 and BiMg 2AsO 6

    NASA Astrophysics Data System (ADS)

    Huang, Jinfan; Gu, Qiuyi; Sleight, Arthur W.

    1993-08-01

    Two new compounds, BiMg 2PO 6 and BiMg 2AsO 6, have been synthesized and structurally characterized by single crystal and powder X-ray diffraction. Both compounds crystallize in the orthorhombic space group Cmcm (No. 63) with four formula units per unit cell. They are isostructural with bismuth magnesium vanadate, BiMg 2VO 6. The cell parameters for BiMg 2PO 6 are a = 7.801(2), b = 11.888(3), c = 5.273(2) Å, V = 489.0(2) Å 3 and for BiMg 2AsO 6 are a = 7.9142(5), b = 12.1637(8), c = 5.3898(4) Å, V = 518.9(2) Å 3. The formula for this series of compounds may be written as (BiO 2)Mg AO 4 to emphasize the (BiO 2) 1- chains and the (AO 4) 3- tetrahedral groups isolated from one another. Between these chains and tetrahedral groups sit Mg 2+ cations in an unusual fivefold coordination to oxygen. No emission bands were observed from BiMg 2PO 6 and BiMg 2AsO 6 under excitation with UV or visible radiation. The IR spectra of these compounds are compared to that of BiMg 2VO 6.

  9. Volcanoes and global catastrophes

    NASA Technical Reports Server (NTRS)

    Simkin, Tom

    1988-01-01

    The search for a single explanation for global mass extinctions has let to polarization and the controversies that are often fueled by widespread media attention. The historic record shows a roughly linear log-log relation between the frequency of explosive volcanic eruptions and the volume of their products. Eruptions such as Mt. St. Helens 1980 produce on the order of 1 cu km of tephra, destroying life over areas in the 10 to 100 sq km range, and take place, on the average, once or twice a decade. Eruptions producing 10 cu km take place several times a century and, like Krakatau 1883, destroy life over 100 to 1000 sq km areas while producing clear global atmospheric effects. Eruptions producting 10,000 cu km are known from the Quaternary record, and extrapolation from the historic record suggests that they occur perhaps once in 20,000 years, but none has occurred in historic time and little is known of their biologic effects. Even larger eruptions must also exist in the geologic record, but documentation of their volume becomes increasingly difficult as their age increases. The conclusion is inescapable that prehistoric eruptions have produced catastrophes on a global scale: only the magnitude of the associated mortality is in question. Differentiation of large magma chambers is on a time scale of thousands to millions of years, and explosive volcanoes are clearly concentrated in narrow belts near converging plate margins. Volcanism cannot be dismissed as a producer of global catastrophes. Its role in major extinctions is likely to be at least contributory and may well be large. More attention should be paid to global effects of the many huge eruptions in the geologic record that dwarf those known in historic time.

  10. Global Volcano Model

    NASA Astrophysics Data System (ADS)

    Sparks, R. S. J.; Loughlin, S. C.; Cottrell, E.; Valentine, G.; Newhall, C.; Jolly, G.; Papale, P.; Takarada, S.; Crosweller, S.; Nayembil, M.; Arora, B.; Lowndes, J.; Connor, C.; Eichelberger, J.; Nadim, F.; Smolka, A.; Michel, G.; Muir-Wood, R.; Horwell, C.

    2012-04-01

    Over 600 million people live close enough to active volcanoes to be affected when they erupt. Volcanic eruptions cause loss of life, significant economic losses and severe disruption to people's lives, as highlighted by the recent eruption of Mount Merapi in Indonesia. The eruption of Eyjafjallajökull, Iceland in 2010 illustrated the potential of even small eruptions to have major impact on the modern world through disruption of complex critical infrastructure and business. The effects in the developing world on economic growth and development can be severe. There is evidence that large eruptions can cause a change in the earth's climate for several years afterwards. Aside from meteor impact and possibly an extreme solar event, very large magnitude explosive volcanic eruptions may be the only natural hazard that could cause a global catastrophe. GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. We are designing and developing an integrated database system of volcanic hazards, vulnerability and exposure with internationally agreed metadata standards. GVM will establish methodologies for analysis of the data (eg vulnerability indices) to inform risk assessment, develop complementary hazards models and create relevant hazards and risk assessment tools. GVM will develop the capability to anticipate future volcanism and its consequences. NERC is funding the start-up of this initiative for three years from November 2011. GVM builds directly on the VOGRIPA project started as part of the GRIP (Global Risk Identification Programme) in 2004 under the auspices of the World Bank and UN. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM.

  11. Boron isotopic composition of fumarolic condensates from some volcanoes in Japanese island arcs

    NASA Astrophysics Data System (ADS)

    Nomura, Masao; Kanzaki, Tadao; Ozawa, Takejiro; Okamoto, Makoto; Kakihana, Hidetake

    1982-11-01

    Boron samples from 40 fumarolic condensates from volcanoes in the Ryukyu arc (Satsuma Iwo-jima and Shiratori Iwo-yama) and the North-east Japan arc (Usu-shinzan, Showa-shinzan, Esan and Issaikyo-yama) all have 11B /10B ratios close to 4.07. Higher values, from 4.09 to 4.13, were only observed in condensates from volcanoes in the southernmost end of the North-east Japan arc (Nasu-dake), the northern part of the Izu-Bonin arc (Hakone), and the North Mariana arc (Ogasawara Iwo-jima). These higher values suggest geological interaction of the magmas with sea-water enriched in 11B.

  12. Relative chronology of Martian volcanoes

    NASA Technical Reports Server (NTRS)

    Landheim, R.; Barlow, N. G.

    1991-01-01

    Impact cratering is one of the major geological processes that has affected the Martian surface throughout the planet's history. The frequency of craters within particular size ranges provides information about the formation ages and obliterative episodes of Martian geologic units. The Barlow chronology was extended by measuring small craters on the volcanoes and a number of standard terrain units. Inclusions of smaller craters in units previously analyzed by Barlow allowed for a more direct comparison between the size-frequency distribution data for volcanoes and established chronology. During this study, 11,486 craters were mapped and identified in the 1.5 to 8 km diameter range in selected regions of Mars. The results are summarized in this three page report and give a more precise estimate of the relative chronology of the Martian volcanoes. Also, the results of this study lend further support to the increasing evidence that volcanism has been a dominant geologic force throughout Martian history.

  13. Remote sensing of volcanos and volcanic terrains

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, Peter J.; Francis, Peter W.; Wilson, Lionel; Pieri, David C.; Self, Stephen; Rose, William I.; Wood, Charles A.

    1989-01-01

    The possibility of using remote sensing to monitor potentially dangerous volcanoes is discussed. Thermal studies of active volcanoes are considered along with using weather satellites to track eruption plumes and radar measurements to study lava flow morphology and topography. The planned use of orbiting platforms to study emissions from volcanoes and the rate of change of volcanic landforms is considered.

  14. Deep structure and origin of active volcanoes in China

    NASA Astrophysics Data System (ADS)

    Zhao, D.

    2010-12-01

    Recent geophysical studies have provided important constraints on the deep structure and origin of the active intraplate volcanoes in Mainland China. Magmatism in the western Pacific arc and back-arc areas is caused by the corner flow in the mantle wedge and dehydration of the subducting slab (e.g., Zhao et al., 2009a), while the intraplate magmatism in China has different origins. The active volcanoes in Northeast China (such as the Changbai and Wudalianchi) are caused by hot upwelling in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well (Zhao et al., 2009b). The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate (or Indian plate) (Lei et al., 2009a). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs' deep subduction in the east and Indian slab's deep subduction in the west down to the lower mantle (Lei et al., 2009b; Zhao, 2009). The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab-plume interactions (Zhao, 2009). References Lei, J., D. Zhao, Y. Su, 2009a. Insight into the origin of the Tengchong intraplate volcano and seismotectonics in southwest China from local and teleseismic data. J. Geophys. Res. 114, B05302. Lei, J., D. Zhao, B. Steinberger et al., 2009b. New seismic constraints on the upper mantle structure of the Hainan plume. Phys. Earth Planet. Inter. 173, 33-50. Zhao, D., 2009. Multiscale seismic tomography and mantle dynamics. Gondwana Res. 15, 297-323. Zhao, D., Z. Wang, N. Umino, A. Hasegawa, 2009a. Mapping the mantle wedge and interplate thrust zone of the northeast Japan arc. Tectonophysics 467, 89-106. Zhao, D., Y. Tian, J. Lei, L. Liu, 2009b. Seismic

  15. Seismic activity of Erebus volcano, antarctica

    NASA Astrophysics Data System (ADS)

    Kaminuma, Katsutada

    1987-11-01

    Mount Erebus is presently the only Antarctic volcano with sustained eruptive activity in the past few years. It is located on Ross Island and a convecting anorthoclase phonolite lava lake has occupied the summit crater of Mount Erebus from January 1973 to September 1984. A program to monitor the seismic activity of Mount Erebus named IMESS was started in December 1980 as an international cooperative program among Japan, the United States and New Zealand. A new volcanic episode began on 13 September, 1984 and continued until December. Our main observations from the seismic activity from 1982 1985 are as follows: (1) The average numbers of earthquakes which occurred around Mount Erebus in 1982, 1983 and January August 1984 were 64, 134 and 146 events per day, respectively. Several earthquake swarms occurred each year. (2) The averag number of earthquakes in 1985 is 23 events per day, with only one earthquake swarm. (3) A remarkable decrease of the background seismicity is recognized before and after the September 1984 activity. (4) Only a few earthquakes were located in the area surrounding Erebus mountain after the September 1984 activity. A magma reservoir is estimated to be located in the southwest area beneath the Erebus summit, based on the hypocenter distributions of earthquakes.

  16. Multiphase modelling of mud volcanoes

    NASA Astrophysics Data System (ADS)

    Colucci, Simone; de'Michieli Vitturi, Mattia; Clarke, Amanda B.

    2015-04-01

    Mud volcanism is a worldwide phenomenon, classically considered as the surface expression of piercement structures rooted in deep-seated over-pressured sediments in compressional tectonic settings. The release of fluids at mud volcanoes during repeated explosive episodes has been documented at numerous sites and the outflows resemble the eruption of basaltic magma. As magma, the material erupted from a mud volcano becomes more fluid and degasses while rising and decompressing. The release of those gases from mud volcanism is estimated to be a significant contributor both to fluid flux from the lithosphere to the hydrosphere, and to the atmospheric budget of some greenhouse gases, particularly methane. For these reasons, we simulated the fluid dynamics of mud volcanoes using a newly-developed compressible multiphase and multidimensional transient solver in the OpenFOAM framework, taking into account the multicomponent nature (CH4, CO2, H2O) of the fluid mixture, the gas exsolution during the ascent and the associated changes in the constitutive properties of the phases. The numerical model has been tested with conditions representative of the LUSI, a mud volcano that has been erupting since May 2006 in the densely populated Sidoarjo regency (East Java, Indonesia), forcing the evacuation of 40,000 people and destroying industry, farmland, and over 10,000 homes. The activity of LUSI mud volcano has been well documented (Vanderkluysen et al., 2014) and here we present a comparison of observed gas fluxes and mud extrusion rates with the outcomes of numerical simulations. Vanderkluysen, L.; Burton, M. R.; Clarke, A. B.; Hartnett, H. E. & Smekens, J.-F. Composition and flux of explosive gas release at LUSI mud volcano (East Java, Indonesia) Geochem. Geophys. Geosyst., Wiley-Blackwell, 2014, 15, 2932-2946

  17. Of Rings and Volcanoes

    NASA Astrophysics Data System (ADS)

    2002-01-01

    show it. The bright spot close to the equator is the remnant of a giant storm in Saturn's extended atmosphere that has lasted more than 5 years. The present photo provides what is possibly the sharpest view of the ring system ever achieved from a ground-based observatory . Many structures are visible, the most obvious being the main ring sections, the inner C-region (here comparatively dark), the middle B-region (here relatively bright) and the outer A-region, and also the obvious dark "divisions", including the well-known, broad Cassini division between the A- and B-regions, as well as the Encke division close to the external edge of the A-region and the Colombo division in the C-region. Moreover, many narrow rings can be seen at this high image resolution , in particular within the C-region - they may be compared with those seen by the Voyager spacecraft during the flybys, cf. the weblinks below. This image demonstrates the capability of NAOS-CONICA to observe also extended objects with excellent spatial resolution. It is a composite of four short-exposure images taken through the near-infrared H (wavelength 1.6 µm) and K (2.2 µm) filters. This observation was particularly difficult because of the motion of Saturn during the exposure. To provide the best possible images, the Adaptive Optics system of NAOS was pointed towards the Saturnian moon Tethys , while the image of Saturn was kept at a fixed position on the CONICA detector by means of "differential tracking" (compensating for the different motions in the sky of Saturn and Tethys). This is also why the (faint) image of Tethys - visible south of Saturn (i.e., below the planet in PR Photo 04a/02 ) - appears slightly trailed. Io - volcanoes and sulphur ESO PR Photo 04b/02 ESO PR Photo 04b/02 [Preview - JPEG: 400 x 478 pix - 39k] [Normal - JPEG: 800 x 955 pix - 112k] ESO PR Photo 04c/02 ESO PR Photo 04c/02 [Preview - JPEG: 400 x 469 pix - 58k] [Normal - JPEG: 800 x 937 pix - 368k] Caption : PR Photo 04b/02 shows

  18. Alaska volcanoes guidebook for teachers

    USGS Publications Warehouse

    Adleman, Jennifer N.

    2011-01-01

    Alaska’s volcanoes, like its abundant glaciers, charismatic wildlife, and wild expanses inspire and ignite scientific curiosity and generate an ever-growing source of questions for students in Alaska and throughout the world. Alaska is home to more than 140 volcanoes, which have been active over the last 2 million years. About 90 of these volcanoes have been active within the last 10,000 years and more than 50 of these have been active since about 1700. The volcanoes in Alaska make up well over three-quarters of volcanoes in the United States that have erupted in the last 200 years. In fact, Alaska’s volcanoes erupt so frequently that it is almost guaranteed that an Alaskan will experience a volcanic eruption in his or her lifetime, and it is likely they will experience more than one. It is hard to imagine a better place for students to explore active volcanism and to understand volcanic hazards, phenomena, and global impacts. Previously developed teachers’ guidebooks with an emphasis on the volcanoes in Hawaii Volcanoes National Park (Mattox, 1994) and Mount Rainier National Park in the Cascade Range (Driedger and others, 2005) provide place-based resources and activities for use in other volcanic regions in the United States. Along the lines of this tradition, this guidebook serves to provide locally relevant and useful resources and activities for the exploration of numerous and truly unique volcanic landscapes in Alaska. This guidebook provides supplemental teaching materials to be used by Alaskan students who will be inspired to become educated and prepared for inevitable future volcanic activity in Alaska. The lessons and activities in this guidebook are meant to supplement and enhance existing science content already being taught in grade levels 6–12. Correlations with Alaska State Science Standards and Grade Level Expectations adopted by the Alaska State Department of Education and Early Development (2006) for grades six through eleven are listed at

  19. Raman spectroscopic study of the mineral arsenogorceixite BaAl3AsO3(OH)(AsO4,PO4)(OH,F)6

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei; Pogson, Ross E.

    2012-06-01

    Arsenogorceixite BaAl3AsO3(OH)(AsO4,PO4)(OH,F)6 belongs to the crandallite mineral subgroup of the alunite supergroup. Arsenogorceixite forms a continuous series of solid solutions with related minerals including gorceixite, goyazite, arsenogoyazite, plumbogummite and philipsbornite. Two minerals from (a) Germany and (b) from Ashburton Downs, Australia were analysed by Raman spectroscopy. The spectra show some commonality but the intensities of the peaks vary. Sharp intense Raman bands for the German sample, are observed at 972 and 814 cm-1 attributed to the ν1 PO43- and AsO43- symmetric stretching modes. Raman bands at 1014, 1057, 1148 and 1160 cm-1 are attributed to the ν1 PO2 symmetric stretching mode and ν3 PO43- antisymmetric stretching vibrations. Raman bands at 764 and 776 cm-1 and 758 and 756 cm-1 are assigned to the ν3 AsO43- antisymmetric stretching vibrations. For the Australian mineral, the ν1 PO43- band is found at 973 cm-1. The intensity of the arsenate bands observed at 814, 838 and 870 cm-1 is greatly enhanced. Two low intensity Raman bands at 1307 and 1332 cm-1 are assigned to hydroxyl deformation modes. The intense Raman band at 441 cm-1 with a shoulder at 462 cm-1 is assigned to the ν2 PO43- bending mode. Raman bands at 318 and 340 cm-1 are attributed to the (AsO4)3-ν2 bending. The broad band centred at 3301 cm-1 is assigned to water stretching vibrations and the sharper peak at 3473 cm-1 is assigned to the OH stretching vibrations. The observation of strong water stretching vibrations brings into question the actual formula of arsenogorceixite. It is proposed the formula is better written as BaAl3AsO3(OH)(AsO4,PO4)(OH,F)6·xH2O. The observation of both phosphate and arsenate bands provides a clear example of solid solution formation.

  20. Academic Libraries in Japan

    ERIC Educational Resources Information Center

    Cullen, Rowena; Nagata, Haruki

    2008-01-01

    Academic libraries in Japan are well resourced by international standards, and support Japan's internationally recognized research capability well, but there are also ways in which they reflect Japan's strong bureaucratic culture. Recent changes to the status of national university libraries have seen a new interest in customer service, and…

  1. Laboratory volcano geodesy

    NASA Astrophysics Data System (ADS)

    Færøvik Johannessen, Rikke; Galland, Olivier; Mair, Karen

    2014-05-01

    intrusion can be excavated and photographed from several angles to compute its 3D shape with the same photogrammetry method. Then, the surface deformation pattern can be directly compared with the shape of underlying intrusion. This quantitative dataset is essential to quantitatively test and validate classical volcano geodetic models.

  2. Io Volcano Observer (IVO)

    NASA Astrophysics Data System (ADS)

    McEwen, A. S.; Keszthelyi, L.; Spencer, J.; Thomas, N.; Johnson, T.; Christensen, P.; Wurz, P.; Glassmeier, K. H.; Shinohara, C.; Girard, T.

    2009-04-01

    In early FY2008, NASA solicited study concepts for Discovery/Scout-class missions that would be enabled by use of 2 Advanced Stirling Radioisotope Generators (ASRGs). We proposed an Io Volcano Observer (IVO) study concept, because the ASRGs enable pointing flexibility and a high data rate from a low-cost mission in Jupiter orbit. Io presents a rich array of inter-connected orbital, geophysical, atmospheric, and plasma phenomena and is the only place in the Solar System (including Earth) where we can watch very large-scale silicate volcanic processes in action. Io is the best place to study tidal heating, which greatly expands the habitable zones of planetary systems. The coupled orbital-tidal evolution of Io and Europa is key to understanding the histories of both worlds. IVO utilizes an elliptical orbit inclined > 45° to Jupiter's orbital plane with repeated fast flybys of Io. Io will have nearly constant illumination at each flyby, which facilitates monitoring of changes over time. The view of Io on approach and departure will be nearly polar, enabling unique measurement and monitoring of polar heat flow (key to tidal heating models), equatorial plumes, and magnetospheric interactions. We expect to collect and return 20 Gbits per flyby via 34-m DSN stations, >1000 times the Io data return of Galileo. The minimal payload we considered included (1) a narrow-angle camera, (2) a thermal mapper, (3) an ion and neutral mass spectrometer, and (4) a pair of fluxgate magnetometers. The camera will acquire global km-scale monitoring and sampling down to 10 m/pixel or better. One key objective is to acquire nearly simultaneous (<0.1 s) multispectral measurements to determine the peak lava temperatures, which in turn constrains the temperature and rheology of Io's mantle and whether or not the heat flow is in equilibrium with tidal heating. The thermal mapper will be similar to THEMIS on Mars Odyssey, but with bandpasses designed to monitor volcanic activity, measure heat

  3. Mount Rainier, a decade volcano

    SciTech Connect

    Kuehn, S.C.; Hooper, P.R. . Dept. of Geology); Eggers, A.E. . Dept. of Geology)

    1993-04-01

    Mount Rainier, recently designated as a decade volcano, is a 14,410 foot landmark which towers over the heavily populated southern Puget Sound Lowland of Washington State. It last erupted in the mid-1800's and is an obvious threat to this area, yet Rainier has received little detailed study. Previous work has divided Rainier into two distinct pre-glacial eruptive episodes and one post-glacial eruptive episode. In a pilot project, the authors analyzed 253 well-located samples from the volcano for 27 major and trace elements. Their objective is to test the value of chemical compositions as a tool in mapping the stratigraphy and understanding the eruptive history of the volcano which they regard as prerequisite to determining the petrogenesis and potential hazard of the volcano. The preliminary data demonstrates that variation between flows is significantly greater than intra-flow variation -- a necessary condition for stratigraphic use. Numerous flows or groups of flows can be distinguished chemically. It is also apparent from the small variation in Zr abundances and considerable variation in such ratios as Ba/Nb that fractional crystallization plays a subordinate role to some form of mixing process in the origin of the Mount Rainier lavas.

  4. What Happened to Our Volcano?

    ERIC Educational Resources Information Center

    Mangiante, Elaine Silva

    2006-01-01

    In this article, the author presents an investigative approach to "understanding Earth changes." The author states that students were familiar with earthquakes and volcanoes in other regions of the world but never considered how the land beneath their feet had experienced changes over time. Here, their geology unit helped them understand and…

  5. On the geometric form of volcanoes - Comment

    NASA Technical Reports Server (NTRS)

    Wood, C. A.

    1982-01-01

    The model of Lacey et al. (1981) accounting for the geometric regularity and approximate cone shape of volcanoes is discussed. It is pointed out that, contrary to the model, volcano eruptions do not occur randomly in elevation and azimuth, but are commonly restricted to summit vents and a few well defined flank zones, so that the form of a volcano is determined by its vent locations and styles of eruption. Other false predictions of the model include the constancy of lava volumes at all vent elevations, the increase in volcano radius as the square root of time, a critical height for volcano growth, the influence of planetary gravity on volcano height and the negligible influence of ash falls and flows and erosional deposition. It is noted that the model of Shteynberg and Solov'yev, in which cone shape is related to stresses due to increasing cone height, may provide a better understanding of volcano morphology.

  6. Iridium emissions from Hawaiian volcanoes

    NASA Technical Reports Server (NTRS)

    Finnegan, D. L.; Zoller, W. H.; Miller, T. M.

    1988-01-01

    Particle and gas samples were collected at Mauna Loa volcano during and after its eruption in March and April, 1984 and at Kilauea volcano in 1983, 1984, and 1985 during various phases of its ongoing activity. In the last two Kilauea sampling missions, samples were collected during eruptive activity. The samples were collected using a filterpack system consisting of a Teflon particle filter followed by a series of 4 base-treated Whatman filters. The samples were analyzed by INAA for over 40 elements. As previously reported in the literature, Ir was first detected on particle filters at the Mauna Loa Observatory and later from non-erupting high temperature vents at Kilauea. Since that time Ir was found in samples collected at Kilauea and Mauna Loa during fountaining activity as well as after eruptive activity. Enrichment factors for Ir in the volcanic fumes range from 10,000 to 100,000 relative to BHVO. Charcoal impregnated filters following a particle filter were collected to see if a significant amount of the Ir was in the gas phase during sample collection. Iridium was found on charcoal filters collected close to the vent, no Ir was found on the charcoal filters. This indicates that all of the Ir is in particulate form very soon after its release. Ratios of Ir to F and Cl were calculated for the samples from Mauna Loa and Kilauea collected during fountaining activity. The implications for the KT Ir anomaly are still unclear though as Ir was not found at volcanoes other than those at Hawaii. Further investigations are needed at other volcanoes to ascertain if basaltic volcanoes other than hot spots have Ir enrichments in their fumes.

  7. Augustine Volcano, Cook Inlet, Alaska (January 31, 2006)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Since last spring, the U.S. Geological Survey's Alaska Volcano Observatory (AVO) has detected increasing volcanic unrest at Augustine Volcano in Cook Inlet, Alaska near Anchorage. Based on all available monitoring data, AVO regards that an eruption similar to 1976 and 1986 is the most probable outcome. During January, activity has been episodic, and characterized by emission of steam and ash plumes, rising to altitudes in excess of 9,000 m (30,000 ft), and posing hazards to aircraft in the vicinity. In the last week, volcanic flows have been seen on the volcano's flanks. An ASTER thermal image was acquired at night at 22:50 AST on January 31, 2006, during an eruptive phase of Augustine. The image shows three volcanic flows down the north flank of Augustine as white (hot) areas. The eruption plume spreads out to the east in a cone shape: it appears dark blue over the summit because it is cold and water ice dominates the composition; further downwind a change to orange color indicates that the plume is thinning and the signal is dominated by the presence of ash.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at

  8. Eruptions on A Virtual Globe: The Aster Volcano Archive

    NASA Astrophysics Data System (ADS)

    Pieri, D. C.; Abrams, M. J.; Tan, H. L.

    2007-12-01

    The systematic study of the world's most frequent volcanic activity is a compelling and productive arena for orbital remote sensing techniques, informing a range of investigations from basic volcanology to societal risk assessments. The Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER--a joint project of Japan and the United States), with its high spatial resolution (15, 30, 90m/pixel), multispectral character (0.52- 0.86μm; 1.6-2.4μm; 8.1-11.6μm), and stereophotogrammetric capability is in many ways an ideal imaging instrument for this task. Since launch in December 1999, an ASTER volcano target list of over 1500 volcanoes has yielded a (still growing) inventory of over 140,000 volcano views on over 70,000 individual ASTER day and night images. A significant emerging challenge for ASTER is how to effectively access a burgeoning data archive in a way that allows the survey, extraction, and distribution of important information in a timely way. This issue is particularly acute in general for ASTER, which has produced a multi-spectral, high spatial resolution, feature-specific targeted global data base of over 1 million image data granules worldwide. To promptly and efficiently access and manage voluminous volcano data within a large ASTER image library, and to house other ancillary correlative volcanological data from MISR, MODIS, EO-1 data sets, SRTM, and related in situ data, we have created a specialty domain called the JPL ASTER Volcano Archive (AVA: http://ava.jpl.nasa.gov). We will discuss and illustrate the myriad challenges and scientific opportunities that this unprecedentedly large, but accessible, global volcanological remote sensing data set represents in terms of data mining, data analysis, and data distribution to the scientific community, to disaster responders, the general public, and to educators, and will conduct a live AVA demonstration. This work was performed at the Jet Propulsion Laboratory-California Institute of

  9. Alaska Volcano Observatory's KML Tools

    NASA Astrophysics Data System (ADS)

    Valcic, L.; Webley, P. W.; Bailey, J. E.; Dehn, J.

    2008-12-01

    Virtual Globes are now giving the scientific community a new medium to present data, which is compatible across multiple disciplines. They also provide scientists the ability to display their data in real-time, a critical factor in hazard assessment. The Alaska Volcano Observatory remote sensing group has developed Keyhole Markup Language (KML) tools that are used to display satellite data for volcano monitoring and forecast ash cloud movement. The KML tools allow an analyst to view the satellite data in a user-friendly web based environment, without a reliance on non-transportable, proprietary software packages. Here, we show how the tools are used operationally for thermal monitoring of volcanic activity, volcanic ash cloud detection and dispersion modeling, using the Puff model. animate.images.alaska.edu/

  10. Venus - Volcano With Massive Landslides

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This Magellan full-resolution mosaic which covers an area 143 by 146 kilometers (89 by 91 miles) is centered at 55 degrees north latitude, 266 degrees east longitude. The bright feature, slightly south of center is interpreted to be a volcano, 15-20 kilometers (9.3 to 12.4 miles) in diameter with a large apron of blocky debris to its right and some smaller aprons to its left. A preferred explanation is that several massive catastrophic landslides dropped down steep slopes and were carried by their momentum out into the smooth, dark lava plains. At the base of the east-facing or largest scallop on the volcano is what appears to be a large block of coherent rock, 8 to 10 kilometers (5 to 6 miles) in length. The similar margin of both the scallop and block and the shape in general is typical of terrestrial slumped blocks (masses of rock which slide and rotate down a slope instead of breaking apart and tumbling). The bright lobe to the south of the volcano may either be a lava flow or finer debris from other landslides. This volcanic feature, characterized by its scalloped flanks is part of a class of volcanoes called scalloped or collapsed domes of which there are more than 80 on Venus. Based on the chute-like shapes of the scallops and the existence of a spectrum of intermediate to well defined examples, it is hypothesized that all of the scallops are remnants of landslides even though the landslide debris is often not visible. Possible explanations for the missing debris are that it may have been covered by lava flows, the debris may have weathered or that the radar may not be recognizing it because the individual blocks are too small

  11. New studies of Martian volcanoes

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, P. J.; Robinson, M. S.; Zisk, S. H.

    1991-01-01

    To investigate the morphology, topography, and evolution of volcanic constructs on Mars, researchers have been studying the volcanoes Olympus Mons, Tyrrhena Patera, and Apollinaris Patera. These studies relied upon the analysis of digital Viking orbiter images to measure the depth and slopes of the summit area of Olympus Mons, upon new Earth-based radar measurements for the analysis of the slopes of Tyrrhena Patera, and upon the color characteristics of the flanks of Apollinaris Patera for information regarding surface properties.

  12. Glaciation of Haleakala volcano, Hawaii

    SciTech Connect

    Moore, J.G.; Mark, R. ); Porter, S.C. . Quaternary Research Center)

    1993-04-01

    Early debates regarding the large (5 [times] 10 km) summit crater'' of Haleakala volcano (3,055 m altitude) on the island of Maui attributed its origin to renting, rifting, caldera collapse, or erosion. It now is commonly assumed to have resulted from headward expansion of giant canyons by stream erosion (Stearns, 1942). Slope maps and shaded relief images based on new USGS digital elevation data point to the apparent overfit of the canyons that drain the summit depression. Studies of drowned coral reefs and terraces on the offshore east rift of Haleakala indicate that this part of the volcano has undergone submergence of about 2 km, as well as tilting, since 850 ka ago. Such subsidence indicates that the summit altitude at the end of the shield-building phase reached ca. 5,000 m, well above both the present and full-glacial snowlines. A comparison with the radiometrically dated glacial record of Mauna Kea and its reconstructed snowline history suggests that Haleakala experienced 10 or more glaciations, the most extensive during marine isotope stages 20, 18, and 16. By isotope stage 10, the summit had subsided below the full-glacial snowline. Diamictons on the south slope of the volcano, previously described as mudflows, contain lava clasts with superchilled margins, identical to margins of subglacially erupted lavas on Mauna Kea. Glacier ice that mantled the upper slopes of the volcano continuously for several hundred thousand years and intermittently thereafter, is inferred to have carved Haleakala crater and the upper reaches of large canyons radiating from it.

  13. Flank tectonics of Martian volcanoes

    SciTech Connect

    Thomas, P.J. ); Squyres, S.W. ); Carr, M.H. )

    1990-08-30

    On the flanks of Olympus Mons is a series of terraces, concentrically distributed around the caldera. Their morphology and location suggest that they could be thrust faults caused by compressional failure of the cone. In an attempt to understand the mechanism of faulting and the possible influences of the interior structure of Olympus Mons, the authors have constructed a numerical model for elastic stresses within a Martian volcano. In the absence of internal pressurization, the middle slopes of the cone are subjected to compressional stress, appropriate to the formation of thrust faults. These stresses for Olympus Mons are {approximately}250 MPa. If a vacant magma chamber is contained within the cone, the region of maximum compressional stress is extended toward the base of the cone. If the magma chamber is pressurized, extensional stresses occur at the summit and on the upper slopes of the cone. For a filled but unpressurized magma chamber, the observed positions of the faults agree well with the calculated region of high compressional stress. Three other volcanoes on Mars, Ascraeus Mons, Arsia Mons, and Pavonis Mons, possess similar terraces. Extending the analysis to other Martian volcanoes, they find that only these three and Olympus Mons have flank stresses that exceed the compressional failure strength of basalt, lending support to the view that the terraces on all four are thrust faults.

  14. Earthquakes - Volcanoes (Causes and Forecast)

    NASA Astrophysics Data System (ADS)

    Tsiapas, E.

    2009-04-01

    EARTHQUAKES - VOLCANOES (CAUSES AND FORECAST) ELIAS TSIAPAS RESEARCHER NEA STYRA, EVIA,GREECE TEL.0302224041057 tsiapas@hol.gr The earthquakes are caused by large quantities of liquids (e.g. H2O, H2S, SO2, ect.) moving through lithosphere and pyrosphere (MOHO discontinuity) till they meet projections (mountains negative projections or projections coming from sinking lithosphere). The liquids are moved from West Eastward carried away by the pyrosphere because of differential speed of rotation of the pyrosphere by the lithosphere. With starting point an earthquake which was noticed at an area and from statistical studies, we know when, where and what rate an earthquake may be, which earthquake is caused by the same quantity of liquids, at the next east region. The forecast of an earthquake ceases to be valid if these components meet a crack in the lithosphere (e.g. limits of lithosphere plates) or a volcano crater. In this case the liquids come out into the atmosphere by the form of gasses carrying small quantities of lava with them (volcano explosion).

  15. 2. PARKING LOT AT JAGGAR MUSEUM, VOLCANO OBSERVATORY. VIEW OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. PARKING LOT AT JAGGAR MUSEUM, VOLCANO OBSERVATORY. VIEW OF MEDIAN. NOTE VOLCANIC STONE CURBING (EDGING) TYPICAL OF MOST PARKING AREAS; TRIANGLING AT END NOT TYPICAL. MAUNA LOA VOLCANO IN BACK. - Crater Rim Drive, Volcano, Hawaii County, HI

  16. Thematic mapper studies of Andean volcanoes

    NASA Technical Reports Server (NTRS)

    Francis, P. W.

    1986-01-01

    The primary objective was to identify all the active volcanoes in the Andean region of Bolivia. Morphological features of the Tata Sabaya volcano, Bolivia, were studied with the thematic mapper. Details include marginal levees on lava and pyroclastic flows, and summit crater structure. Valley glacier moraine deposits, not easily identified on the multispectral band scanner, were also unambiguous, and provide useful marker horizons on large volcanic edifices which were built up in preglacial times but which were active subsequently. With such high resolution imagery, it is not only possible to identify potentially active volcanoes, but also to use standard photogeological interpretation to outline the history of individual volcanoes.

  17. ASO: Antistreptolysin O titer

    MedlinePlus

    Advertisement Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services. Advertising & Sponsorship: Policy | Opportunities PLEASE NOTE: Your web browser ...

  18. The Pressure Sources Beneath Unzen Volcano Inferred From Geodesic Survey

    NASA Astrophysics Data System (ADS)

    Kohno, Y.; Matsushima, T.; Shimizu, H.

    2004-12-01

    Unzen Volcano, which is located on Shimabara Peninsula, west Kyushu Island, Japan, erupted from 1990 to 1995. The ground deformations caused by volcanic activity were observed by several methods, such as Leveling survey, GPS and Tilt meters. In particular, it turned out from leveling data that the west coast area of Shimabara Peninsula sank about 8 cm since eruption had started. Joint Research Team of the national Universities suggested in 1992 that the model which has three pressure sources, could explain the ground deformation data in those days. But this model couldn_ft explain the leveling data which was observed after the eruption had stopped. In order to explain this latest leveling data, we had to add the fourth deeper pressure source beneath the Chidiwa Bay, confronted in the west seashore of the Shimabara peninsula (Matsushima et al., 2003; Kohno et al., 2003). In this study, we re-consider the source model beneath Unzen Volcano, using 1991-2001 and 2004 Leveling data along the northern flank of Unzen Volcano and the western coast of Shimabara peninsula. Also we use GPS data monitored by Kyushu University and Geographical Survey Institute. In calculation, both vertical and horizontal displacement was calculated applying the point source model (e.g. Mogi, 1958), and we get the best-fit source parameters. Parameters of the pressure sources are the location and the volume changes of pressure sources. Through the model calculation, the half-infinite surface was made for every height of each observation point, and geographical feature was reproduced in approximation. Analysis showed that after 1995 shallower source had started to deflate, on the other hand, two deeper sources still had kept expanding caused by intrusion of magma. After 1999, three shallower sources had begun to contract, and the only deepest (a depth of 15 km) source had expanded. But it is inferred from the 2004 Leveling that the deepest source turned to contract since 2001, and the all

  19. Newberry Volcano (Oregon, USA) Revised

    NASA Astrophysics Data System (ADS)

    Donnelly-Nolan, J. M.; Grove, T. L.

    2015-12-01

    Newberry Volcano (NV) located E. of the Cascades arc axis is often interpreted as (1) a High Lava Plains (NW Basin & Range -- B&R) volcano hosting rhyolites generated by a traveling plume, (2) a shield volcano built of basalt, or (3) an enigma unrelated to the adjacent High Cascades. Recent work shows that these interpretations are incorrect. Petrologic, geochemical, isotopic, drill hole, & seismic data indicate that the NV magma system results from arc-related processes at the NW corner of the B&R, where this major extensional province impinges on the Cascades arc. NV rhyolites are geochemically distinct and lower in SiO2 than those to the east where a general NW-younging trend of rhyolite ages has suggested a traveling hotspot -- a consequence instead of propagation of B&R extension. NV lies ~90 km above the downgoing slab based on seismic evidence (McCrory et al. 2012), ~15 km deeper than under the Three Sisters (TS) volcanic complex 60 km to the NW on the arc axis. NV & TS exhibit a range of compositions and both have generated rhyodacite with unusually high Na2O contents (~7 wt. %; Mandler et al. 2014), exhibiting similar petrogenetic processes. Silicic lavas and tuffs of the caldera-centric NV make up a significant component (~20% of drill core) of its 600 km3, although basaltic andesite is the dominant composition. Basalts of calcalkaline affinity erupted on the edifice as recently as early Holocene time. These basalts contain petrologic evidence for high pre-eruptive H2O contents, have strong arc-like trace element signatures, and are isotopically Cascadian and distinct from basalts to the east in the B&R that have much higher 3/4He (Graham et al. 2009). NV is one variety of Cascades arc volcano among which are a range of stratovolcanoes including Mt. Baker (15 km3) and Mt. Shasta (500 km3), a Holocene caldera (Crater Lake), and the many basaltic andesite shield volcanoes that make up most of the Oregon High Cascades.

  20. Crystal chemistry of anhydrous Li uranyl phosphates and arsenates. II. Tubular fragments and cation-cation interactions in the 3D framework structures of Li 6[(UO 2) 12(PO 4) 8(P 4O 13)], Li 5[(UO 2) 13(AsO 4) 9(As 2O 7)], Li[(UO 2) 4(AsO 4) 3] and Li 3[(UO 2) 7(AsO 4) 5O)

    NASA Astrophysics Data System (ADS)

    Alekseev, Evgeny V.; Krivovichev, Sergey V.; Depmeier, Wulf

    2009-11-01

    Single crystals of the new compounds Li 6[(UO 2) 12(PO 4) 8(P 4O 13)] ( 1), Li 5[(UO 2) 13(AsO 4) 9(As 2O 7)] ( 2), Li[(UO 2) 4(AsO 4) 3] ( 3) and Li 3[(UO 2) 7(AsO 4) 5O)] ( 4) have been prepared using high-temperature solid state reactions. The crystal structures have been solved by direct methods: 1—monoclinic, C2/ m, a=26.963(3) Å, b=7.063(1) Å, c=19.639(1) Å, β=126.890(4)°, V=2991.2(6) Å 3, Z=2, R1=0.0357 for 3248 unique reflections with | F0|≥4 σ F; 2—triclinic, P1¯, a=7.1410(8) Å, b=13.959(1) Å, c=31.925(1) Å, α=82.850(2)°, β=88.691(2)°, γ=79.774(3)°, V=3107.4(4) Å 3, Z=2, R1=0.0722 for 9161 unique reflections with | F0|≥4 σ F; 3—tetragonal, I4 1/ amd, a=7.160(3) Å, c=33.775(9) Å, V=1732(1) Å 3, Z=4, R1=0.0356 for 318 unique reflections with | F0|≥4 σ F; 4—tetragonal, P4¯, a=7.2160(5) Å, c=14.6540(7) Å, V=763.04(8) Å 3, Z=1, R1=0.0423 for 1600 unique reflections with | F0|≥4 σ F. Structures of all the phases under consideration are based on complex 3D frameworks consisting of different types of uranium polyhedra (UO 6 and UO 7) and different types of tetrahedral TO 4 anions ( T=P or As): PO 4 and P 4O 13 in 1, AsO 4 and As 2O 7 in 2, and single AsO 4 tetrahedra in 3 and 4. In the structures of 1 and 2, UO 7 pentagonal bipyramids share edges to form (UO 5) ∞ chains extended along the b axis in 1 and along the a axis in 2. The chains are linked via single TO 4 tetrahedra into tubular units with external diameters of 11 Å in 1 and 11.5 Å in 2, and internal diameters of 4.1 Å in 1 and 4.5 Å in 2. The channels accommodate Li + cations. The tubular units are linked into 3D frameworks by intertubular complexes. Structures of 3 and 4 are based on 3D frameworks composed on layers united by (UO 5) ∞ infinite chains. Cation-cation interactions are observed in 2, 3, and 4. In 2, the structure contains a trimeric unit with composition [OU(1)O]-U(13)-[OU(2)O]. In the structures of 3 and 4, T-shaped dimers are

  1. Electrical resistivity tomography study of Taal volcano hydrothermal system, Philippines

    NASA Astrophysics Data System (ADS)

    Fikos, I.; Vargemezis, G.; Zlotnicki, J.; Puertollano, J. R.; Alanis, P. B.; Pigtain, R. C.; Villacorte, E. U.; Malipot, G. A.; Sasai, Y.

    2012-10-01

    Taal volcano (311 m in altitude) is located in The Philippines (14°N, 121°E) and since 1572 has erupted 33 times, causing more than 2,000 casualties during the most violent eruptions. In March 2010, the shallow structures in areas where present-day surface activity takes place were investigated by DC resistivity surveys. Electrical resistivity tomography (ERT) lines were performed above the two identified hydrothermal areas located on the northern flank of the volcano and in the Main Crater, respectively. Due to rough topography, deep valleys, and dense vegetation, most measurements were collected using a remote method based on a laboratory-made equipment. This allowed retrieval of information down to a depth of 250 m. ERTs results detail the outlines of the two geothermal fields defined by previous self-potential, CO2 soil degassing, ground temperature, and magnetic mapping (Harada et al. Japan Acad Sci 81:261-266, 2005; Zlotnicki et al. Bull Volcanol 71:29-49, 2009a, Phys Chem Earth 34:294-408, 2009b). Hydrothermal fluids originate mainly from inside the northern part of the Main Crater at a depth greater than the bottom of the Crater Lake, and flow upward to the ground surface. Furthermore, water from the Main Crater Lake infiltrates inside the surrounding geological formations. The hydrothermal fluids, outlined by gas releases and high temperatures, cross the crater rim and interact with the northern geothermal field located outside the Main Crater.

  2. Remote sensing for active volcano monitoring in Barren Island, India

    SciTech Connect

    Bhattacharya, A.; Reddy, C.S.S.; Srivastav, S.K. )

    1993-08-01

    The Barren Island Volcano, situated in the Andaman Sea of the Bay of Bengal, erupted recently (March, 1991) after a prolonged period of quiescence of about 188 years. This resumed activity coincides with similar outbreaks in the Philippines and Japan, which are located in an identical tectonic environment. This study addresses (1) remote sensing temporal monitoring of the volcanic activity, (2) detecting hot lava and measuring its pixel-integrated and subpixel temperatures, and (3) the importance of SWIR bands for high temperature volcanic feature detection. Seven sets of TM data acquired continuously from 3 March 1991 to 8 July 1991 have been analyzed. It is concluded that detectable pre-eruption warming took place around 25 March 1991 and volcanic activity started on 1 April 1991. It is observed that high temperature features, such as an erupting volcano, can register emitted thermal radiance in SWIR bands. Calculation of pixel-integrated and sub-pixel temperatures related to volcanic vents has been made, using the dual-band method. 6 refs.

  3. Why did we lose the 59 climbers in 2014 Ontake Volcano Eruption?

    NASA Astrophysics Data System (ADS)

    Kimata, F.

    2015-12-01

    The first historical eruption at Ontake volcano, central Japan was in 1979, and it was a phreatic eruption. Until then, most Japanese volcanologists understood that Ontake is a dormant or an extinct volcano. Re-examination of active volcanoes was done after the eruption.After the first historical eruption in 1979, two small eruptions are repeated in 1991 and 2007. Through the three eruptions, nobody has got injured. The last eruption on September 27, 2014, we lost 65 people included missing. Because it was fine weekend and there were many climbers on the summit. The eruption was almost at lunchtime. Clearly, casualties by tsunamis are inhabitants along the coastlines, and casualties by eruption are visitors not inhabitants around the volcano. Basically, visitors have small information of Ontake volcano. After the accident, one mountain guide tells us that we never have long broken such as lunch around the summit, because an active creator is close, and they are afraid of the volcano gas accidents. All casualties by eruption were lost their lives in the area of 1.0 km distance from the 2014 creators. In 2004 Sumatra Earthquake Tsunami, we could not recognize the tsunami inspiration between the habitants in Banda Aceh, Sumatra. They have no idea of tsunami, and they called "Rising Sea" never"Tsunami". As the result, they lost many habitants close to the coast. In 2011 Tohoku Earthquake Tsunami, when habitants felt strong shaking close to coast, they understood the tsunami coming. 0ver 50 % habitants decide to evacuate from the coast. However, 20-30 % habitants believe in themselves no tsunami attacking for them. As a result we lost many habitants. Additionally, the tsunami height was higher than broadcasting one by JMA. According to the results of the questionnaire survey in climbers or bereaved families of the eruption day on Ontake volcano (Shinano Mainich Newspaper, 2015), 39 % of them were climbing no understand of "Ontake active volcano". Moreover, only 10

  4. Preparing for Routine Satellite Global Volcano Deformation Observations: The Volcano Deformation Database Task Force

    NASA Astrophysics Data System (ADS)

    Pritchard, M. E.; Jay, J.; Andrews, B. J.; Cooper, J.; Henderson, S. T.; Delgado, F.; Biggs, J.; Ebmeier, S. K.

    2014-12-01

    Satellite Interferometric Synthetic Aperture Radar (InSAR) has greatly expanded the number volcanoes that can be monitored for ground deformation - the number of known deforming volcanoes has increased almost five-fold since 1997 (to more than 213 volcanoes in 2014). However, from 1992-2014, there are still gaps in global volcano surveillance and only a fraction of the 1400 subaerial Holocene volcanoes have frequent observations in this time period. Starting in 2014, near global observations of volcano deformation should begin with the Sentinel satellites from the European Space Agency, ALOS-2 from the Japanese Space Agency, and eventually NISAR from the Indian Space Agency and NASA. With more frequent observations, more volcano deformation episodes are sure to be observed, but evaluating the significance of the observed deformation is not always straightforward -- how can we determine if deformation will lead to eruption? To answer this question, an international task force has been formed to create an inventory of volcano deformation events as part of the Global Volcano Model (http://globalvolcanomodel.org/gvm-task-forces/volcano-deformation-database/). We present the first results from our global study focusing on volcanoes that have few or no previous studies. In some cases, there is a lack of SAR data (for example, volcanoes of the South Sandwich Islands). For others, observations either show an absence of deformation or possible deformation that requires more data to be verified. An example of a deforming volcano that has few past studies is Pagan, an island in the Marianas Arc comprised of 2 stratovolcanoes within calderas. Our new InSAR measurements from both the ALOS and Envisat satellites show deformation near the 1981 May VEI 4 lava flow eruption on North Pagan at 2-3 cm/year between 2004-2010. Another example of a newly observed volcano is Karthala volcano in the Comoros. InSAR observations between 2004-2010 span four eruptions, only one of which is

  5. A Raman spectroscopic study of the arsenate mineral chenevixite Cu2Fe2(3+)(AsO4)2(OH)4⋅H2O.

    PubMed

    Frost, Ray L; López, Andrés; Scholz, Ricardo; Lana, Cristiano; Xi, Yunfei

    2015-01-25

    We have studied the mineral chenevixite from Manto Cuba Mine, San Pedro de Cachiyuyo District, Inca de Oro, Chañaral Province, Atacama Region, Chile, using a combination of scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDX) and vibrational spectroscopy. Qualitative chemical analysis shows a homogeneous composition, with predominance of As, Fe, Al, Cu, Fe and Cu. Minor amounts of Si were also observed. Raman spectroscopy complimented with infrared spectroscopy has been used to assess the molecular structure of the arsenate minerals chenevixite. Characteristic Raman and infrared bands of the (AsO4)(3-) stretching and bending vibrations are identified and described. The observation of multiple bands in the (AsO4)(3-) bending region offers support for the loss of symmetry of the arsenate anion in the structure of chenevixite. Raman bands attributable to the OH stretching vibrations of water and hydroxyl units were analysed. Estimates of the hydrogen bond distances were made based upon the OH stretching wavenumbers. PMID:25064502

  6. Influence of UV rays on Feulgen-type staining with azure A-SO2 prepared with normal hydrochloric acid and sodium thiosulphate.

    PubMed

    Dutt, M K

    1981-07-01

    This communication presents a new method for the preparation of azure A-SO2 for use in Feulgen procedure. The salient feature of this method lies in the fact that azure A-SO2 can be decolourised with normal hydrochloric acid and sodium thiosulphate. The pH of this dye reagent is 2.3 and it is of water colour after filtration. The pH of this dye-reagent is raised to 4.0 with an aqueous solution of sodium hydroxide. Nuclear colouration with this newly developed dye-reagent on acid-hydrolysed DNA of tissue sections becomes fairly satisfactory under the usual laboratory conditions. Staining with this dye-reagent under exposure to UV ray is, however, vastly improved within 5 minutes as compared with the control. Stained sections do withstand treatment in SO2 water without exhibiting any leaching of the dye from the nuclei. Possible mode of action of UV rays in increasing the intensity of staining as well as the speed of reaction has been suggested. PMID:6167839

  7. Synthesis, crystal structure, electrical properties, and sodium transport pathways of the new arsenate Na4Co7(AsO4)6

    NASA Astrophysics Data System (ADS)

    Ben Smida, Youssef; Marzouki, Riadh; Georges, Samuel; Kutteh, Ramzi; Avdeev, Maxim; Guesmi, Abderrahmen; Zid, Mohamed Faouzi

    2016-07-01

    A new sodium cobalt (II) arsenate Na4Co7(AsO4)6 has been synthesized by a solid-state reaction and its crystal structure determined from single crystal X-ray diffraction data. It crystallizes in the monoclinic system, space group C2/m, with a=10.7098(9) Å, b=14.7837(9) Å, c=6.6845(7) Å, and β=105.545(9)°. The structure is described as a three-dimensional framework built up of corner-edge sharing CoO6, CoO4 and AsO4 polyhedra, with interconnecting channels along [100] in which the Na+ cations are located. The densest ceramics with relative density of 94% was obtained by ball milling and optimization of sintering temperature, and its microstructure characterized by scanning electron microscopy. The electrical properties of the ceramics were studied over a temperature interval from 280 °C to 560 °C using the complex impedance spectroscopy over the range of 13 MHz-5 Hz. The ionic bulk conductivity value of the sample at 360 °C is 2.51 10-5 S cm-1 and the measured activation energy is Ea=1 eV. The sodium migration pathways in the crystal structure were investigated computationally using the bond valence site energy (BVSE) model and classical molecular dynamics (MD) simulations.

  8. A Raman spectroscopic study of the arsenate mineral chenevixite Cu2Fe23+(AsO4)2(OH)4ṡH2O

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo; Lana, Cristiano; Xi, Yunfei

    2015-01-01

    We have studied the mineral chenevixite from Manto Cuba Mine, San Pedro de Cachiyuyo District, Inca de Oro, Chañaral Province, Atacama Region, Chile, using a combination of scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDX) and vibrational spectroscopy. Qualitative chemical analysis shows a homogeneous composition, with predominance of As, Fe, Al, Cu, Fe and Cu. Minor amounts of Si were also observed. Raman spectroscopy complimented with infrared spectroscopy has been used to assess the molecular structure of the arsenate minerals chenevixite. Characteristic Raman and infrared bands of the (AsO4)3- stretching and bending vibrations are identified and described. The observation of multiple bands in the (AsO4)3- bending region offers support for the loss of symmetry of the arsenate anion in the structure of chenevixite. Raman bands attributable to the OH stretching vibrations of water and hydroxyl units were analysed. Estimates of the hydrogen bond distances were made based upon the OH stretching wavenumbers.

  9. [{Ni4 (OH)3 AsO4 }4 (B-α-PW9 O34 )4 ](28-) : A New Polyoxometalate Structural Family with Catalytic Hydrogen Evolution Activity.

    PubMed

    Lv, Hongjin; Chi, Yingnan; van Leusen, Jan; Kögerler, Paul; Chen, Zheyuan; Bacsa, John; Geletii, Yurii V; Guo, Weiwei; Lian, Tianquan; Hill, Craig L

    2015-11-23

    A new structural polyoxometalate motif, [{Ni4 (OH)3 AsO4 }4 (B-α-PW9 O34 )4 ](28-) , which contains the highest nuclearity structurally characterized multi-nickel-containing polyanion to date, has been synthesized and characterized by single-crystal X-ray diffraction, temperature-dependent magnetism and several other techniques. The unique central {Ni16 (OH)12 O4 (AsO4 )4 } core shows dominant ferromagnetic exchange interactions, with maximum χm T of 69.21 cm(3)  K mol(-1) at 3.4 K. Significantly, this structurally unprecedented complex is an efficient, water-compatible, noble-metal-free catalyst for H2 production upon visible light irradiation (photosensitizer=[Ir(ppy)2 (dtbbpy)][PF6 ]; sacrificial electron donor=triethylamine or triethanolamine). The highest turnover number of approximately 580, corresponding to a best quantum yield of approximately 4.07 %, is achieved when using triethylamine as electron donor in the presence of water. The mechanism of this photodriven process has been probed by time-solved luminescence and by static emission quenching. PMID:26448510

  10. Journey to Japan

    ERIC Educational Resources Information Center

    Godfrey, Lorraine

    1978-01-01

    Create a variety of activities related to the country you are studying--Japan, for example--and arrange them by such subjects as art, games, creative writing, maps, dress and greetings. These activities can be tied in with classroom learning centers or stations. Here students make passports, learn about traditional styles of dress in Japan, learn…

  11. Island of Okinawa, Japan

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The island of Okinawa, (26.5N, 128.0E) largest of the Ryukyu Islands, Japan. The Ryukyu island group lies south of the main home islands of Japan in an arc towards the Chinese island Republic of Taiwan. As is typical throughout the Japanese home islands, intense urban development can be observed all over the island in this near vertical view.

  12. TWELVE DOORS TO JAPAN.

    ERIC Educational Resources Information Center

    BEARDSLEY, RICHARD K.; HALL, JOHN WHITNEY

    THE TWELVE DOORS OF THIS COLLEGE-LEVEL TEXT ARE TWELVE CHAPTERS ON ASPECTS OF JAPAN AND JAPANESE CULTURE AS TREATED BY VARIOUS ACADEMIC DISCIPLINES. THE AUTHORS' PURPOSE IN CHOOSING THIS FORMAT WAS TO PRESENT INTRODUCTORY INFORMATION ABOUT JAPAN AND TO ACQUAINT STUDENTS WITH THE AIMS, MATERIALS, AND METHODS OF DISCIPLINES OTHER THAN THE ONE THEY…

  13. Teaching English in Japan.

    ERIC Educational Resources Information Center

    Kitao, Kenji, Ed.; And Others

    English language instruction, which is considered very important in Japan, is offered in 90 percent of all secondary schools and is studied by almost all students, even though it is an elective subject. English is considered a cultural and commercial link with the western world and has been taught in Japan since the mid-nineteenth century. Most…

  14. Rehabilitation in Japan, 1988.

    ERIC Educational Resources Information Center

    Japanese Society for Rehabilitation of the Disabled, Tokyo.

    The scope of Japan's rehabilitation services for persons with disabilities is reviewed and discussed from the perspective of social and demographic change in that country. An introductory chapter on the current situation in Japan looks at characteristics of the land, the people, the government, industry and the economy, and the culture. The second…

  15. Seismic exploration of Fuji volcano with active sources in 2003

    NASA Astrophysics Data System (ADS)

    Oikawa, J.; Kagiyama, T.; Tanaka, S.; Miyamachi, H.; Tsutsui, T.; Ikeda, Y.; Katayama, H.; Matsuo, N.; Oshima, H.; Nishimura, Y.; Yamamoto, K.; Watanabe, T.; Yamazaki, F.

    2004-12-01

    Fuji volcano (altitude 3,776 m) is the largest basaltic stratovolcano in Japan. In late August and early September 2003, seismic exploration was conducted around Fuji volcano by the detonation of 500 kg charges of dynamite to investigate the seismic structure of that area. Seismographs with an eigenfrequency of 2 Hz were used for observation, positioned along a WSW-ENE line passing through the summit of the mountain. A total of 469 observation points were installed at intervals of 250-500 m. The data were stored in memory on-site using data loggers. The sampling interval was 4 ms. Charges were detonated at 5 points, one at each end of the observation line and 3 along its length. The first arrival times at each observation point for each detonation were recorded as data. The P-wave velocity structure directly below the observation line was determined by forward calculation using the ray tracing method [Zelt and Smith, 1992]. The P-wave velocity structure below the volcano, assuming a layered structure, was found to be as follows. (1) The first layer extends for about 40 km around the summit and to a depth of 1-2 km. The P-wave velocity is 2.5 km/s on the upper surface of the layer and 3.5 km/s on the lower interface. (2) The second layer has P-wave velocities of 4.0 km/s on the top interface and 5.5 km/s at the lower interface. The layer is 25 km thick to the west of the summit and 1-2 km thick to the east, and forms a dome shape with a peak altitude of 2000 m directly below the summit. (3) The third layer is 5-12 km thick and has P-wave velocities of 5.7 km/s at the top interface and 6.5 km/s at the lower interface. This layer reaches shallower levels to the east of the summit, corresponding to the area where the second layer is thinner. Mt. Fuji is located slightly back from where the Philippine Sea Plate subducts below the Eurasian plate in association with collision with the Izu Peninsula. Matsuda (1971) suggested that Mt. Fuji lies on the same uplifted body as

  16. Double Glacier Volcano, a 'new' Quaternary volcano in the eastern Aleutian volcanic arc

    USGS Publications Warehouse

    Reed, B.L.; Lanphere, M.A.; Miller, T.P.

    1992-01-01

    The Double Glacier Volcano (DGV) is a small dome complex of porphyritic hornblende andesite and dacite that is part of the Cook Inlet segment of Quaternary volcanoes of the eastern Aleutian arc. Its discovery reduces the previously described large volcano gap in Cook Inlet segment to a distance similar to that between other volcanoes in the area. DGV lavas are medium-K, calcalkaline andesites and dacites with concentrations of major and minor elements similar to the other Quaternary volcanoes of the Cook Inlet segment. Available K-Ar ages indicate that DGV was active 600-900 ka. ?? 1992 Springer-Verlag.

  17. Smithsonian Volcano Data on Google Earth

    NASA Astrophysics Data System (ADS)

    Venzke, E.; Siebert, L.; Luhr, J. F.

    2006-12-01

    Interactive global satellite imagery datasets such as hosted by Google Earth provide a dynamic platform for educational outreach in the Earth Sciences. Users with widely varied backgrounds can easily view geologic features on a global-to-local scale, giving access to educational background on individual geologic features or events such as volcanoes and earthquakes. The Smithsonian Institution's Global Volcanism Program (GVP) volcano data became available as a Google Earth layer on 11 June 2006. Locations for about 1550 volcanoes with known or possible Holocene activity are shown as red triangles with associated volcano names that appear when zooming in to a regional-scale view. Clicking on a triangle opens an informational balloon that displays a photo, geographic data, and a brief paragraph summarizing the volcano's geologic history. The balloon contains links to a larger version of the photo with credits and a caption and to more detailed information on the volcano, including eruption chronologies, from the GVP website. Links to USGS and international volcano observatories or other websites focusing on regional volcanoes are also provided, giving the user ready access to a broad spectrum of volcano data. Updates to the GVP volcano layer will be provided to Google Earth. A downloadable file with the volcanoes organized regionally is also available directly from the GVP website (www.volcano.si.edu) and provides the most current volcano data set. Limitations of the implied accuracy of spacially plotted data at high zoom levels are also apparent using platforms such as Google Earth. Real and apparent mismatches between plotted locations and the summits of some volcanoes seen in Google Earth satellite imagery occur for reasons including data precision (deg/min vs. deg/min/sec) and the GVP convention of plotting the center-point of large volcanic fields, which often do not correspond to specific volcanic vents. A more fundamental problem originates from the fact that

  18. Active Volcanoes of the Kurile Islands: A Reference Guide for Aviation Users

    USGS Publications Warehouse

    Neal, Christina A.; Rybin, Alexander; Chibisova, Marina; Miller, Edward

    2008-01-01

    Introduction: The many volcanoes of the remote and mostly uninhabited Kurile Island arc (fig. 1; table 1) pose a serious hazard for air traffic in the North Pacific. Ash clouds from Kurile eruptions can impact some of the busiest air travel routes in the world and drift quickly into airspace managed by three countries: Russia, Japan, and the United States. Prevailing westerly winds throughout the region will most commonly send ash from any Kurile eruption directly across the parallel North Pacific airways between North America and Asia (Kristine A. Nelson, National Weather Service, oral commun., 2006; fig. 1). This report presents maps showing locations of the 36 most active Kurile volcanoes plotted on Operational Navigational Charts published by the Defense Mapping Agency (map sheets ONC F-10, F-11, and E-10; figs. 1, 2, 3, 4). These maps are intended to assist aviation and other users in the identification of restless Kurile volcanoes. A regional map is followed by three subsections of the Kurile volcanic arc (North, Central, South). Volcanoes and selected primary geographic features are labeled. All maps contain schematic versions of the principal air routes and selected air navigational fixes in this region.

  19. Geoflicks Reviewed--Films about Hawaiian Volcanoes.

    ERIC Educational Resources Information Center

    Bykerk-Kauffman, Ann

    1994-01-01

    Reviews 11 films on volcanic eruptions in the United States. Films are given a one- to five-star rating and the film's year, length, source and price are listed. Top films include "Inside Hawaiian Volcanoes" and "Kilauea: Close up of an Active Volcano." (AIM)

  20. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... 46-degree forward-viewing cameras of the Eyjafjallajökull volcano and its erupting ash plume. In addition to the main plume, there are ... is necessary to separate out wind and height (see  Volcano Plume Heights ). To view the image in 3-D, use red/blue glasses with ...

  1. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Ash from Eyjafjallajökull Volcano, Iceland Stretches over the North Atlantic   ... that occurred in late March 2010, the Eyjafjallajökull Volcano in Iceland began erupting again on April 14, 2010. The resulting ash ...

  2. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... height map   Ash from Iceland's Eyjafjallajökull volcano, viewed here in imagery from the Multi-angle Imaging SpectroRadiometer ... natural-color, nadir (vertical) view of the scene, with the volcano itself located outside the upper left corner of the image. The ash ...

  3. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... to capture a series of images of the Eyjafjallajökull volcano and its erupting ash plume. Figure 1 is a view from MISR's nadir ... The companion image, Figure 2, is a stereo anaglyph (see  Volcano Plume Heights Anaglyph ) generated from the nadir and 46-degree ...

  4. Orographic Flow over an Active Volcano

    NASA Astrophysics Data System (ADS)

    Poulidis, Alexandros-Panagiotis; Renfrew, Ian; Matthews, Adrian

    2014-05-01

    Orographic flows over and around an isolated volcano are studied through a series of numerical model experiments. The volcano top has a heated surface, so can be thought of as "active" but not erupting. A series of simulations with different atmospheric conditions and using both idealised and realistic configurations of the Weather Research and Forecast (WRF) model have been carried out. The study is based on the Soufriere Hills volcano, located on the island of Montserrat in the Caribbean. This is a dome-building volcano, leading to a sharp increase in the surface skin temperature at the top of the volcano - up to tens of degrees higher than ambient values. The majority of the simulations use an idealised topography, in order for the results to have general applicability to similar-sized volcanoes located in the tropics. The model is initialised with idealised atmospheric soundings, representative of qualitatively different atmospheric conditions from the rainy season in the tropics. The simulations reveal significant changes to the orographic flow response, depending upon the size of the temperature anomaly and the atmospheric conditions. The flow regime and characteristic features such as gravity waves, orographic clouds and orographic rainfall patterns can all be qualitatively changed by the surface heating anomaly. Orographic rainfall over the volcano can be significantly enhanced with increased temperature anomaly. The implications for the eruptive behaviour of the volcano and resulting secondary volcanic hazards will also be discussed.

  5. Volcano Flank Terraces on Mars

    NASA Astrophysics Data System (ADS)

    Byrne, P. K.; van Wyk de Vries, B.; Murray, J. B.; Troll, V. R.

    2008-12-01

    Flank terraces are bulge-like structures that occur on the slopes of at least nine large shield volcanoes on Mars, and three on Earth. Terraces have a convex-upward, convex-outward morphology, with an imbricate "fish scale" stacking pattern in plan. They occur at all elevations, are scale-invariant structures, and have similar proportions to thrust faults on Earth. Suggested mechanisms of formation include elastic self-loading, lithospheric flexure, magma chamber tumescence, flank relaxation, and shallow gravitational slumping. Terrace geometries predicted by most of these mechanisms do not agree with our observations, however. Only lithospheric flexure can fully account for terrace geometry on Mars and Earth, and so is the most likely candidate mechanism for flank terrace formation. To verify this hypothesis, we conducted scaled analogue modelling experiments, and investigated the structures formed during flexure. Cones of a sand-gypsum mix were placed upon a deep layer of silicone gel, to simulate volcanic loads upon viscoelastic Martian crust. Key parameters were varied across our experimental program. In all cases convex topographic structures developed on the cones' flanks, arranged in an imbricate, overlapping plan-view pattern. These structures closely resemble flank terraces observed on Mars, and our results provide for a basic kinematic model of terrace formation. Analogue volcanoes experienced a decrease in upper surface area whilst volume was conserved; the contractional surface strain was accommodated by outward verging, circumferentially striking thrusts. The morphology of experimental structures suggests an orientation of the principal stress axes of σ1 = radial, σ2 = concentric, and σ3 = vertical. Elsewhere (J. B. Murray et al., this volume) we detail the relationship between flank terraces and other structures such as pit craters and gräben, using Ascraeus Mons as a case study. We suggest that terraces may influence the distribution and location

  6. Analytical volcano deformation source models

    USGS Publications Warehouse

    Lisowski, Michael

    2007-01-01

    Primary volcanic landforms are created by the ascent and eruption of magma. The ascending magma displaces and interacts with surrounding rock and fluids as it creates new pathways, flows through cracks or conduits, vesiculates, and accumulates in underground reservoirs. The formation of new pathways and pressure changes within existing conduits and reservoirs stress and deform the surrounding rock. Eruption products load the crust. The pattern and rate of surface deformation around volcanoes reflect the tectonic and volcanic processes transmitted to the surface through the mechanical properties of the crust.

  7. Isotopic composition of gases from mud volcanoes

    SciTech Connect

    Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.; Prokhorov, V.S.; Titkov, G.A.

    1985-09-01

    A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as well as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.

  8. Costa Rica's Chain of laterally collapsed volcanoes.

    NASA Astrophysics Data System (ADS)

    Duarte, E.; Fernandez, E.

    2007-05-01

    From the NW extreme to the SW end of Costa Rica's volcanic backbone, a number of laterally collapsed volcanoes can be observed. Due to several factors, attention has been given to active volcanoes disregarding the importance of collapsed features in terms of assessing volcanic hazards for future generations around inhabited volcanoes. In several cases the typical horseshoe shape amphitheater-like depression can be easily observed. In other cases due to erosion, vegetation, topography, seismic activity or drastic weather such characteristics are not easily recognized. In the order mentioned above appear: Orosi-Cacao, Miravalles, Platanar, Congo, Von Frantzius, Cacho Negro and Turrialba volcanoes. Due to limited studies on these structures it is unknown if sector collapse occurred in one or several phases. Furthermore, in the few studied cases no evidence has been found to relate collapses to actual eruptive episodes. Detailed studies on the deposits and materials composing dome-like shapes will shed light on unsolved questions about petrological and chemical composition. Volume, form and distance traveled by deposits are part of the questions surrounding most of these collapsed volcanoes. Although most of these mentioned structures are extinct, at least Irazú volcano (active volcano) has faced partial lateral collapses recently. It did presented strombolian activity in the early 60s. Collapse scars show on the NW flank show important mass removal in historic and prehistoric times. Moreover, in 1994 a minor hydrothermal explosion provoked the weakening of a deeply altered wall that holds a crater lake (150m diameter, 2.6x106 ). A poster will depict images of the collapsed volcanoes named above with mayor descriptive characteristics. It will also focus on the importance of deeper studies to assess the collapse potential of Irazú volcano with related consequences. Finally, this initiative will invite researchers interested in such topic to join future studies in

  9. Groundwater contamination in Japan

    NASA Astrophysics Data System (ADS)

    Tase, Norio

    1992-07-01

    Problems on groundwater contamination in Japan are briefly summarized in this paper. Although normal physical conditions in Japan restrict the possibilities of groundwater contamination, human activities are threatening groundwater resources. A survey by the Environment Agency of Japan showed nationwide spreading of organic substances, such as trichloroethylene as well as nitrogen compounds. Synthetic detergents have also been detected even in rural areas and in deep confined aquifers, although their concentrations are not as high. Public awareness of agrichemical or pesticides abuse, especially from golf courses, is apparent. Other problems such as nitrate-nitrogen, leachate from landfills, and the leaking of underground storage tanks are also discussed.

  10. Improved detection of preeruptive seismic velocity drops at the Piton de La Fournaise volcano

    NASA Astrophysics Data System (ADS)

    Rivet, Diane; Brenguier, Florent; Cappa, Frédéric

    2015-08-01

    The unexpected 2014 and 2015 Ontake (Japan) and Calbuco (Chile) eruptions proved that improving volcanic eruption prediction is still a great challenge. Decreases of seismic velocities of the Piton de la Fournaise volcano inferred from seismic noise correlations have been shown to precede eruptions. However, seismic velocities are strongly influenced by rainfall and subsequent pore pressure perturbations. Here we increase the detection of precursory seismic velocity changes to an eruption by removing the effects of pore pressure changes. During 2011-2013, the volcano exhibits a low eruptive activity during which we observe seismic velocity variations well correlated with rainfall episodes. We estimated the transfer function between fluid pressure and seismic velocity changes. We use these results to correct seismic velocity change time series for pore pressure changes, due to rainfall and found a preeruptive velocity drop (0.15%) associated with the 21 June 2014 eruption that was undetected before correction.

  11. Estimate of sulfate emitted from Sakurajima volcano to the Japanese Islands

    SciTech Connect

    Mizuno, Tateki; Maeda, Takahisa; Tanaka, Chie; Takeuchi, Kiyohide

    1996-12-31

    Concentration of sulfate increased in a summer night over the wide area of the Kanto plain. Since the effect of long range transport of particulate sulfurs was suggested, Lagrangian dispersion-advection analysis of particles was carried out using global scale weather analytical data. Results show that the concentration observed at the Kanto plain coupled be increased by the effect of the volcanic gas which had been emitted from an active volcano {open_quotes}Sakurajima{close_quotes}, located in the distance of about 1,00 km at south-west of the Kanto area, before 3 days. This phenomenon suggests that sulfate emitted from the active volcano Sakurajima might affect acid deposition of all over the Japanese Islands. This report shows estimated concentration of deposition of sulfate from Sakurajima to the Japan Islands using the same model applied to the Kanto area.

  12. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano.

    PubMed

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-01-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards. PMID:26892716

  13. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano

    NASA Astrophysics Data System (ADS)

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-02-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards.

  14. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano

    PubMed Central

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-01-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards. PMID:26892716

  15. Distribution, geochemistry and age of the Millennium eruptives of Changbaishan volcano, Northeast China -- A review

    NASA Astrophysics Data System (ADS)

    Sun, Chunqing; You, Haitao; Liu, Jiaqi; Li, Xin; Gao, Jinliang; Chen, Shuangshuang

    2014-04-01

    Large explosive volcanic eruptions generate extensive regional tephra deposits that provide favorable conditions for identifying the source of volcanoes, comparing the sedimentary strata of a region and determining their ages. The tephra layer, referred to as BTm, generated by the Millennium eruption of Changbaishan volcano, is widely distributed in Northeast China, Japan, D.P.R. Korea, and the nearby coastal area of Russia. It forms part of the widespread northeast Asian strata and is significant for establishing an isochronal stratigraphic framework. However, research on the temporal characterization and stratigraphic correlation of associated strata using this tephra layer is mainly concentrated in and near Japan. In northeastern China, this tephra layer is seldom seen and its application in stratigraphic correlations is even rarer. More importantly, the determination of accurate ages for both distal and proximal tephras has been debated, leading to controversy in discussions of its environmental impacts. Stratigraphic records from both distal and proximal Changbaishan ash show that this eruption generally occurred between 1,012 and 1,004 cal yr BP. Geochemical comparison between Changbaishan ash and the Quaternary widespread ash around Japan illustrates that Changbaishan ash is a continuous composition from rhyolitic to trachytic and its ratio of FeOT to CaO is usually greater than 4, which can be used as a distinguishing identifier among worldwide contemporary eruptions.

  16. Distribution, geochemistry and age of the Millennium eruptives of Changbaishan volcano, Northeast China — A review

    NASA Astrophysics Data System (ADS)

    Sun, Chunqing; You, Haitao; Liu, Jiaqi; Li, Xin; Gao, Jinliang; Chen, Shuangshuang

    2014-06-01

    Large explosive volcanic eruptions generate extensive regional tephra deposits that provide favorable conditions for identifying the source of volcanoes, comparing the sedimentary strata of a region and determining their ages. The tephra layer, referred to as B-Tm, generated by the Millennium eruption of Changbaishan volcano, is widely distributed in Northeast China, Japan, D.P.R. Korea, and the nearby coastal area of Russia. It forms part of the widespread northeast Asian strata and is significant for establishing an isochronal stratigraphic framework. However, research on the temporal characterization and stratigraphic correlation of associated strata using this tephra layer is mainly concentrated in and near Japan. In northeastern China, this tephra layer is seldom seen and its application in stratigraphic correlations is even rarer. More importantly, the determination of accurate ages for both distal and proximal tephras has been debated, leading to controversy in discussions of its environmental impacts. Stratigraphic records from both distal and proximal Changbaishan ash show that this eruption generally occurred between 1,012 and 1,004 cal yr BP. Geochemical comparison between Changbaishan ash and the Quaternary widespread ash around Japan illustrates that Changbaishan ash is a continuous composition from rhyolitic to trachytic and its ratio of FeOT to CaO is usually greater than 4, which can be used as a distinguishing identifier among worldwide contemporary eruptions.

  17. DEM-based model for reconstructing volcano's morphology from primary volcanic landforms

    NASA Astrophysics Data System (ADS)

    Gayer, Eric; Lopez, Philippe; Michon, Laurent

    2014-05-01

    Volumes of magma intruded in and emitted by volcanoes through time can be estimated by reconstruction of volcano's morphology and time sequence. Classical approaches for quantifying magma volumes on active volcanoes are based on the difference between pre- and post-eruption digital elevation models (DEM), but this kind of approach needs the pre-eruptive surfaces to be available. For old and eroded volcanoes these surfaces are poorly constrained. However, because the geometrical form of many volcanic edifices exhibits a remarkable symmetry we propose, here, a new approach using primary volcanic landforms in order to estimate the amount of the both erupted and eroded material and to locate eruptive centers. A large fraction of composite volcanoes have near constant slope on their flanks and a form that is concave upwards near their summits. But many phenomena can lead to non-symetrical edifices and complex morphologies can result, for example from parasitic centers of volcanism on the flanks, from alternation of short effusive and explosive construction phases, from flank or caldera collapses, or from glacial and other types of erosion. In this study we propose that, on the first order approximation, complex morphologies can be modeled by piling regular cones. In this model, cones centers and slopes are derived by fitting primary volcanic landform with a linear function :elevation=f(distance from center). Such an approach allows to estimate both errors on location of the eruptive center and on the volume of the resulting cones. This model can then be used for quantifying volume of erupted and eroded material, and for quantifying catastrophic events as giant landslides or flank collapse. This approach is tested on four different active volcanoes : Mount Mayon (Philippines), Mount Fuji (Japan), Mount Etna (Sicily) and Mount Teide (Canary Island) to estimate errors in volume between modeled and actual edifices. It is then used on volcanoes of La Réunion hotspot to

  18. Volcanic Landform Classification of Iwate Volcano from DEM-Derived Thematic Maps

    NASA Astrophysics Data System (ADS)

    Prima, A. O.; Yoshida, T.

    2004-12-01

    Over the last three decades, digital elevation models (DEMs) have been developed as surface data instead of contour lines to allow numerical analysis or modeling of terrain by computer. DEMs have allowed the development of algorithms to rapidly derive slope, relief, convexity, concavity and aspect of any points of surface, and also have allowed the definition of a number of new morphometric measures i.e. openness (Yokoyama et al., 2002). Openness is an angular measure of the relation between surface relief and horizontal distance. Openness has two viewer perspectives. Positive values, expressing openness above the surface, are high for convex forms, whereas negative values describe this attribute below the surface and are high for concave forms. The emphasis of terrain convexity and concavity in openness maps facilitates the interpretation of landforms on the Earth_fs surface. Prima et al. (2003) proposed automated landform classification using openness and slope with genetic factors. This method had been proved to produce good classification for constructional (alluvial plains, alluvial fans and volcanoes) and erosional (hills and mountains) landforms. The capability of this method to classify landforms from DEMs with genetic factors is important because it allows landform evolution to be numerically analyzed. In this study, we adopted this method to classify volcanic landforms of Iwate Volcano from Honshu, Japan, where volcanic landforms were categorized referring to geological map of Iwate Volcano (Doi, 2000). This process took three steps. First, the characteristic of each category was evaluated against the mean and standard deviation of slope, and both positive and negative openness, in two dimensional feature spaces. Second, the characteristic of each category were observed and the combinations of mean and standard deviation of slope and openness showing high separabilities were selected. We found that the standard deviation of slope, positive and negative

  19. Monoclinic structure of hydroxylpyromorphite Pb10(PO4)6(OH)2 - hydroxylmimetite Pb10(AsO4)6(OH)2 solid solution series

    NASA Astrophysics Data System (ADS)

    Giera, Alicja; Manecki, Maciej; Borkiewicz, Olaf; Zelek, Sylwia; Rakovan, John; Bajda, Tomasz; Marchlewski, Tomasz

    2016-04-01

    Seven samples of hydroxyl analogues of pyromorphite-mimetite solid solutions series were synthesized from aqueous solutions at 80° C in a computer-controlled chemistate: 200 mL aqueous solutions of 0.05M Pb(NO3)2 and 0.03M KH2AsO4 and/or KH2PO4 were dosed with a 0.25 mL/min rate to a glass beaker, which initially contained 100 mL of distilled water. Constant pH of 8 was maintained using 2M KOH. The syntheses yielded homogeneous fine-grained white precipitates composition of which was close to theoretical Pb10[(PO4)6‑x(AsO4)x](OH)2, where x = 0, 1, 2, 3, 4, 5, 6. High-resolution powder X-ray diffraction data were obtained in transmission geometry at the beamline 11-BM at the Advanced Photon Source (Argonne National Laboratory in Illinois, USA). The structure Rietveld refinements based on starting parameters of either hexagonal hydroxylpyromorphite or monoclinic mimetite-M were performed using GSAS+EXPGUI software. Apatite usually crystallizes in the hexagonal crystal system with the space group P63/m. For the first time, however, the lowering of the hexagonal to monoclinic crystal symmetry was observed in the hydroxyl variety of pyromorphite-mimetite solid solution series. This is indicated by better fitting of the modeled monoclinic structure to the experimental data. The same is not the case for analogous calcium hydroxylapatite series Ca5(PO4)3OH - Ca5(AsO4)3OH (Lee et al. 2009). Systematical linear increase of unit cell parameters is observed with As substitution from a=9.88, b=19.75, and c=7.43 for Pb10(PO4)6(OH)2 to a=10.23, b=20.32, and c=7.51 for Pb10(AsO4)6(OH)2. A strong pseudohexagonal character (γ ≈ 120° and b ≈ 2a) of the analyzed monoclinic phases was established. This work is partially funded by AGH research grant no 11.11.140.319 and partially by Polish NCN grant No 2011/01/M/ST10/06999. Lee Y.J., Stephens P.W., Tang Y., Li W., Philips B.L., Parise J.B., Reeder R.J., 2009. Arsenate substitution in hydroxylapatite: Structural characterization

  20. GPM Arrives in Japan

    NASA Video Gallery

    An international satellite that will set a new standard for global precipitation measurements from space has completed a 7,300-mile journey from the United States to Japan, where it now will underg...

  1. Space communications in Japan

    NASA Astrophysics Data System (ADS)

    Mori, T.

    This paper outlines some of the planned satellite comunication projects in Japan over the next 5-7 years. In addition, Japanese space development policies are set out along with a historic review of the development of artificial satellites.

  2. Exploring Geology on the World-Wide Web--Volcanoes and Volcanism.

    ERIC Educational Resources Information Center

    Schimmrich, Steven Henry; Gore, Pamela J. W.

    1996-01-01

    Focuses on sites on the World Wide Web that offer information about volcanoes. Web sites are classified into areas of Global Volcano Information, Volcanoes in Hawaii, Volcanoes in Alaska, Volcanoes in the Cascades, European and Icelandic Volcanoes, Extraterrestrial Volcanism, Volcanic Ash and Weather, and Volcano Resource Directories. Suggestions…

  3. Borehole Strain Measurements on Volcanoes: Insights from Montserrat and Hekla

    NASA Astrophysics Data System (ADS)

    Linde, A. T.; Sacks, S. I.

    2010-12-01

    In Fall 2000 we reported that data from Sacks-Evertson borehole strainmeters allowed a short term (~20 minutes) warning of an eruption of Hekla, Iceland, in 2000 and showed clear changes before an eruption of Izu-Oshima, Japan, in 1986. In 2002-2003 (CALIPSO program) we installed a small net of strainmeters near Montserrat’s Soufriere Hills Volcano, an active andesitic dome building volcano. We have sites in Long Valley and Hawaii (with USGS); at Vesuvius, Campi Flegrei area, Stromboli and (planned) Etna (with Italian colleagues). Gladwin strainmeters have been installed at Yellowstone and Mt. St. Helens (PBO). Our recent volcano research efforts have been on Montserrat and Hekla. Analyses of a very large dome collapse (Montserrat) in July 2003 (Voight et al, 2006) and an explosion in March 2004 (Linde et al., 2010) reveal a reservoir at about 5 km with a NW-SE trending dike extending from the reservoir to about 1.5 km from the surface. A number of explosions require only a narrow conduit (15 m radius) that extends from the top of the dike to the surface (Voight et al. 2010); others have a different strain signature and require deeper sources. A 1 month long clear strain excursion required an additional contribution from a reservoir at about 11 km (Hautmann et al. in prep). Many small signals with similar strain change patterns take place over much shorter time scales (2 - 20 mins) are presumably due to gas transfer. We now realize, from the 2000 eruption of Hekla, that the magma geometry is quite different from that in all earlier models. The reservoir is about 11 km deep but the dike that breaks the surface in Hekla's characteristic fissure eruption does not extend to the reservoir as had been thought; but to no more than about 1 km. Although undetectable by any available surface measurements, there must be a conduit to connect the reservoir to the dike. In Sturkell et al. (in prep) we propose that this conduit is now sufficiently large in diameter to remain

  4. Instrumentation Recommendations for Volcano Monitoring at U.S. Volcanoes Under the National Volcano Early Warning System

    USGS Publications Warehouse

    Moran, Seth C.; Freymueller, Jeff T.; LaHusen, Richard G.; McGee, Kenneth A.; Poland, Michael P.; Power, John A.; Schmidt, David A.; Schneider, David J.; Stephens, George; Werner, Cynthia A.; White, Randall A.

    2008-01-01

    As magma moves toward the surface, it interacts with anything in its path: hydrothermal systems, cooling magma bodies from previous eruptions, and (or) the surrounding 'country rock'. Magma also undergoes significant changes in its physical properties as pressure and temperature conditions change along its path. These interactions and changes lead to a range of geophysical and geochemical phenomena. The goal of volcano monitoring is to detect and correctly interpret such phenomena in order to provide early and accurate warnings of impending eruptions. Given the well-documented hazards posed by volcanoes to both ground-based populations (for example, Blong, 1984; Scott, 1989) and aviation (for example, Neal and others, 1997; Miller and Casadevall, 2000), volcano monitoring is critical for public safety and hazard mitigation. Only with adequate monitoring systems in place can volcano observatories provide accurate and timely forecasts and alerts of possible eruptive activity. At most U.S. volcanoes, observatories traditionally have employed a two-component approach to volcano monitoring: (1) install instrumentation sufficient to detect unrest at volcanic systems likely to erupt in the not-too-distant future; and (2) once unrest is detected, install any instrumentation needed for eruption prediction and monitoring. This reactive approach is problematic, however, for two reasons. 1. At many volcanoes, rapid installation of new ground-1. based instruments is difficult or impossible. Factors that complicate rapid response include (a) eruptions that are preceded by short (hours to days) precursory sequences of geophysical and (or) geochemical activity, as occurred at Mount Redoubt (Alaska) in 1989 (24 hours), Anatahan (Mariana Islands) in 2003 (6 hours), and Mount St. Helens (Washington) in 1980 and 2004 (7 and 8 days, respectively); (b) inclement weather conditions, which may prohibit installation of new equipment for days, weeks, or even months, particularly at

  5. A global database of composite volcano morphometry

    NASA Astrophysics Data System (ADS)

    Grosse, Pablo; Euillades, Pablo A.; Euillades, Leonardo D.; van Wyk de Vries, Benjamin

    2014-01-01

    We present a global database on the subaerial morphometry of composite volcanoes. Data was extracted from the 90-m resolution Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). The 759 volcanoes included in the database are the composite (i.e., polygenetic) volcanoes listed in the Smithsonian Institution Global Volcanism Program (GVP) database that are covered by the SRTM DEM, have a constructional topography and a basal width larger than 2 km. The extent of each volcano edifice was defined using the NETVOLC algorithm, which computes outlines by minimizing a cost function based on breaks in slope around the edifices. Morphometric parameters were then calculated using the MORVOLC algorithm. The parameters characterize and quantify volcano size (basal width, summit width, height, and volume), profile shape (height/basal width and summit width/basal width ratios), plan shape (ellipticity and irregularity indexes), and slopes. In addition, 104 well-defined and relatively large summit craters/calderas were manually delineated and specific parameters were computed. Most parameters show large variation without clear separations, indicating a continuum of volcano morphologies. Large overlap between the main GVP morphologic types highlights the need for a more rigorous quantitative classification of volcano morphology. The database will be maintained and updated through a website under construction.

  6. A scale for ranking volcanoes by risk

    NASA Astrophysics Data System (ADS)

    Scandone, Roberto; Bartolini, Stefania; Martí, Joan

    2016-01-01

    We propose a simple volcanic risk coefficient (VRC) useful for comparing the degree of risk arising from different volcanoes, which may be used by civil protection agencies and volcano observatories to rapidly allocate limited resources even without a detailed knowledge of each volcano. Volcanic risk coefficient is given by the sum of the volcanic explosivity index (VEI) of the maximum expected eruption from the volcano, the logarithm of the eruption rate, and the logarithm of the population that may be affected by the maximum expected eruption. We show how to apply the method to rank the risk using as examples the volcanoes of Italy and in the Canary Islands. Moreover, we demonstrate that the maximum theoretical volcanic risk coefficient is 17 and pertains to the large caldera-forming volcanoes like Toba or Yellowstone that may affect the life of the entire planet. We develop also a simple plugin for a dedicated Quantum Geographic Information System (QGIS) software to graphically display the VRC of different volcanoes in a region.

  7. Mud Volcanoes - Analogs to Martian Cones and Domes (by the Thousands!)

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy

    2010-01-01

    laboratory analyses of surface samples collected from mud volcanoes in Azerbaijan, Taiwan and Japan. X-ray diffraction, visible / near infrared reflectance spectroscopy and Raman spectroscopy show that the samples are dominated by mixed-layer smectite clays, along with quartz, calcite and pyrite. Thin section analysis by optical and scanning electron microscopy confirms the mineral identifications. These samples also contain chemical and morphological biosignatures, including common microfossils, with evidence of partial replacement by pyrite. The bulk samples contain approximately 1 wt% total organic carbon and 0.4 mg / gm volatile hydrocarbons. The thousands of features in Acidalia Planitia cited as analogous to terrestrial mud volcanoes clearly represent an important element in the sedimentary record of Mars. Their location, in the distal depocenter for massive Hesperian-age floods, suggests that they contain fine-grained sediments from a large catchment area in the martian highlands. We have proposed these features as a new class of exploration target that can provide access to minimally-altered material from significant depth. By analogy to terrestrial mud volcanoes, these features may also be excellent sites for the sampling martian organics and subsurface microbial life, if such exist or ever existed.

  8. Conditions of deep magma chamber beneath Fuji volcano estimated from high- P experiments

    NASA Astrophysics Data System (ADS)

    Asano, K.; Takahashi, E.; Hamada, M.; Ushioda, M.; Suzuki, T.

    2012-12-01

    Fuji volcano, the largest in volume and eruption rate in Japan, is located at the center of Honshu, where North America, Eurasia and Philippine Sea plates meets. Because of the significance of Fuji volcano both in tectonic settings and potential volcanic hazard (particularly after the M9 earthquake in 2011), precise knowledge on its magma feeding system is essentially important. Composition of magma erupted from Fuji volcano in the last 100ky is predominantly basalt (SiO2=50-52wt%, FeO/MgO=1.5-3.0). Total lack of silica-rich magma (basaltic andesite and andesite) which are always present in other nearby volcanoes (e.g., Hakone, Izu-Oshima, see Fig.1) is an important petrologic feature of Fuji volcano. Purpose of this study is to constrain the depth of magma chamber of Fuji volcano and explain its silica-nonenrichment trend. High pressure melting experiments were carried out using two IHPVs at the Magma Factory, Tokyo Institute of Technology (SMC-5000 and SMC-8600, Tomiya et al., 2010). Basalt scoria Tr-1 which represents the final ejecta of Hoei eruption in AD1707, was adopted as a starting material. At 4kbar, temperature conditions were 1050, 1100 and 1150C, and H2O contents were 1.3, 2.7 and 4.7 wt.%, respectively. At 7kbar, temperature conditions were 1075, 1100 and 1125C, and H2O contents were 1.0, 1.1, 3.6 and 6.3wt.%, respectively. The fO2 was controlled at NNO buffer. At 4kbar, crystallization sequence at 3 wt% H2O is magnetite, plagioclase, clinopyroxene and finally orthopyroxene. At 7 kbar, and ~3 wt% H2O, the three minerals (opx, cpx, pl) appears simultaneously near the liquidus. Compositional trend of melt at 4 kbar and 7 kbar are shown with arrows in Fig.1. Because of the dominant crystallization of silica-rich opx at 7 kbar, composition of melt stays in the range SiO2=50-52wt% as predicted by Fujii (2007). Absence of silica-rich rocks in Fuji volcano may be explained by the tectonic setting of the volcano. Because Fuji volcano locates on the plate

  9. Volcanoes

    MedlinePlus

    ... also cause earthquakes, mudflows and flash floods, rock falls and landslides, acid rain, fires, and even tsunamis. Volcanic gas and ash can damage the lungs of small infants, older adults, and people with severe respiratory illnesses. Volcanic ash can affect ...

  10. Volcanoes

    MedlinePlus

    ... Hazards Preventing Violence Pressure Washer Safety High-Pressure Water Injection Injury Trench Foot or Immersion Foot Emergency Wound Care Wound Management for Healthcare Pros Power Outages When the Power Goes Out Worker Safety ...

  11. Volcanoes

    MedlinePlus

    ... is a vent in the Earth's crust. Hot rock, steam, poisonous gases, and ash reach the Earth's ... can also cause earthquakes, mudflows and flash floods, rock falls and landslides, acid rain, fires, and even ...

  12. Volcanoes

    MedlinePlus

    ... Hazardous Materials Incidents Home Fires Household Chemical Emergencies Hurricanes Landslides & Debris Flow Nuclear Blast Nuclear Power Plants ... Hazardous Materials Incidents Home Fires Household Chemical Emergencies Hurricanes Landslides & Debris Flow Nuclear Blast Nuclear Power Plants ...

  13. Volcanoes

    MedlinePlus

    ... a Flood Worker Safety Educational Materials Floods PSAs Hurricanes Before a Hurricane Make a Plan Get Supplies Get Your Family, ... Ready Evacuate or Stay at Home After a Hurricane Make Sure Your Food and Water Are Safe ...

  14. Volcano geodesy: The search for magma reservoirs and the formation of eruptive vents

    USGS Publications Warehouse

    Dvorak, J.J.; Dzurisin, D.

    1997-01-01

    Routine geodetic measurements are made at only a few dozen of the world's 600 or so active volcanoes, even though these measurements have proven to be a reliable precursor of eruptions. The pattern and rate of surface displacement reveal the depth and rate of pressure increase within shallow magma reservoirs. This process has been demonstrated clearly at Kilauea and Mauna Loa, Hawaii; Long Valley caldera, California; Campi Flegrei caldera, Italy; Rabaul caldera, Papua New Guinea; and Aira caldera and nearby Sakurajima, Japan. Slower and lesser amounts of surface displacement at Yellowstone caldera, Wyoming, are attributed to changes in a hydrothermal system that overlies a crustal magma body. The vertical and horizontal dimensions of eruptive fissures, as well as the amount of widening, have been determined at Kilauea, Hawaii; Etna, Italy; Tolbachik, Kamchatka; Krafla, Iceland; and Asal-Ghoubbet, Djibouti, the last a segment of the East Africa Rift Zone. Continuously recording instruments, such as tiltmeters, extensometers, and dilatometers, have recorded horizontal and upward growth of eruptive fissures, which grew at rates of hundreds of meters per hour, at Kilauea; Izu-Oshima, Japan; Teishi Knoll seamount, Japan; and Piton de la Fournaise, Re??union Island. In addition, such instruments have recorded the hour or less of slight ground movement that preceded small explosive eruptions at Sakurajima and presumed sudden gas emissions at Galeras, Colombia. The use of satellite geodesy, in particular the Global Positioning System, offers the possibility of revealing changes in surface strain both local to a volcano and over a broad region that includes the volcano.

  15. Linking space observations to volcano observatories in Latin America: Results from the CEOS DRM Volcano Pilot

    NASA Astrophysics Data System (ADS)

    Delgado, F.; Pritchard, M. E.; Biggs, J.; Arnold, D. W. D.; Poland, M. P.; Ebmeier, S. K.; Wauthier, C.; Wnuk, K.; Parker, A. L.; Amelug, F.; Sansosti, E.; Mothes, P. A.; Macedo, O.; Lara, L.; Zoffoli, S.; Aguilar, V.

    2015-12-01

    Within Latin American, about 315 volcanoes that have been active in the Holocene, but according to the United Nations Global Assessment of Risk 2015 report (GAR15) 202 of these volcanoes have no seismic, deformation or gas monitoring. Following the 2012 Santorini Report on satellite Earth Observation and Geohazards, the Committee on Earth Observation Satellites (CEOS) has developed a 3-year pilot project to demonstrate how satellite observations can be used to monitor large numbers of volcanoes cost-effectively, particularly in areas with scarce instrumentation and/or difficult access. The pilot aims to improve disaster risk management (DRM) by working directly with the volcano observatories that are governmentally responsible for volcano monitoring, and the project is possible thanks to data provided at no cost by international space agencies (ESA, CSA, ASI, DLR, JAXA, NASA, CNES). Here we highlight several examples of how satellite observations have been used by volcano observatories during the last 18 months to monitor volcanoes and respond to crises -- for example the 2013-2014 unrest episode at Cerro Negro/Chiles (Ecuador-Colombia border); the 2015 eruptions of Villarrica and Calbuco volcanoes, Chile; the 2013-present unrest and eruptions at Sabancaya and Ubinas volcanoes, Peru; the 2015 unrest at Guallatiri volcano, Chile; and the 2012-present rapid uplift at Cordon Caulle, Chile. Our primary tool is measurements of ground deformation made by Interferometric Synthetic Aperture Radar (InSAR) but thermal and outgassing data have been used in a few cases. InSAR data have helped to determine the alert level at these volcanoes, served as an independent check on ground sensors, guided the deployment of ground instruments, and aided situational awareness. We will describe several lessons learned about the type of data products and information that are most needed by the volcano observatories in different countries.

  16. Small Volcano in Terra Cimmeria

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 26 June 2002) The Science This positive relief feature (see MOLA context) in the ancient highlands of Mars appears to be a heavily eroded volcanic center. The top of this feature appears to be under attack by the erosive forces of the martian wind. Light-toned streaks are visible, trending northeast to southwest, and may be caused by scouring of the terrain, or they may be dune forms moving sand. The northeast portion of the caldera area looks as though a layer of material is being removed to expose a slightly lighter-toned surface underneath. The flanks of this feature are slightly less cratered than the surrounding terrain, which could be explained in two ways: 1) this feature may be younger than the surrounding area, and has had less time to accumulate meteorite impacts, or 2) the slopes that are observed today may be so heavily eroded that the original, cratered surfaces are now gone, exposing relatively uncratered rocks. Although most of Terra Cimmeria has low albedo, some eastern portions, such as shown in this image, demonstrate an overall lack of contrast that attests to the presence of a layer of dust mantling the surface. This dust, in part, is responsible for the muted appearance and infill of many of the craters at the northern and southern ends of this image The Story This flat-topped volcano pops out from the surface, the swirls of its ancient lava flows running down onto the ancient highlands of Mars. Its smooth top appears to be under attack by the erosive forces of the martian wind. How can you tell? Click on the image above for a close-up look. You'll see some light-toned streaks that run in a northeast-southwest direction. They are caused either by the scouring of the terrain or dunes of moving sand. Either way, the wind likely plays upon the volcano's surface. Look also for the subtle, nearly crescent shaped feature at the northeast portion of the volcano's cap. It looks as if a layer of material has been removed by the wind, exposing

  17. Volcanoes can muddle the greenhouse

    SciTech Connect

    Kerr, R.A.

    1990-01-01

    As scientists and politicians anxiously eye signs of global greenhouse warming, climatologists are finding the best evidence yet that a massive volcanic eruption can temporarily bring the temperature down a notch or two. Such a cooling could be enough to set the current global warming back more than a decade, confusing any efforts to link it to the greenhouse effect. By effectively eliminating some nonvolcanic climate changes from the record of the past 100 years, researchers have detected drops in global temperature of several tenths of a degree within 1 to 2 years of volcanic eruptions. Apparently, the debris spewed into the stratosphere blocked sunlight and caused the temperature drops. For all their potential social significance, the climate effects of volcanoes have been hard to detect. The problem has been in identifying a volcanic cooling among the nearly continuous climate warmings and coolings of a similar size that fill the record. The paper reviews how this was done.

  18. The hydrogeology of Kilauea volcano

    SciTech Connect

    Ingebritsen, S.E.; Scholl, M.A. )

    1993-08-01

    The hydrogeology of Kilauea volcano and adjacent areas has been studied since the turn of this century. However, most studies to date have focused on the relatively shallow, low-salinity parts of the ground-water system, and the deeper hydrothermal system remains poorly understood. The rift zones of adjacent Mauna Loa volcano bound the regional ground-water flow system that includes Kilauea, and the area bounded by the rift zones of Kilauea and the ocean may comprise a partly isolated subsystem. Rates of ground-water recharge vary greatly over the area, and discharge is difficult to measure, because streams are ephemeral and most ground-water discharges diffusely at or below sea level. Hydrothermal systems exist at depth in Kilauea's east and southwest rift zone, as evidenced by thermal springs at the coast and wells in the lower east-rift zone. Available data suggest that dike-impounded, heated ground water occurs at relatively high elevations in the upper east- and southwest-rift zones of Kilauea, and that permeability at depth in the rift zones. Available data suggest that dike-impounded, heated ground water occurs at relatively high elevations in the upper east- and southwest-rift zones of Kilauea, and that permeability at depth in the rift zones (probably [le]10[sup [minus]15] m[sup 2]) is much lower than that of unaltered basalt flows closer to the surface ([ge]10[sup [minus]10] m[sup 2]). Substantial variations in permeability and the presence of magmatic heat sources influence that structure of the fresh water-salt water interface, so the Ghyben-Herzberg model will often fail to predict its position. Numerical modeling studies have considered only subsets of the hydrothermal system, because no existing computer code solves the coupled fluid-flow, heat- and solute-transport problem over the temperature and salinity range encountered at Kilauea. 73 refs., 7 figs., 2 tabs.

  19. Earthquake sources near Uturuncu Volcano

    NASA Astrophysics Data System (ADS)

    Keyson, L.; West, M. E.

    2013-12-01

    Uturuncu, located in southern Bolivia near the Chile and Argentina border, is a dacitic volcano that was last active 270 ka. It is a part of the Altiplano-Puna Volcanic Complex, which spans 50,000 km2 and is comprised of a series of ignimbrite flare-ups since ~23 ma. Two sets of evidence suggest that the region is underlain by a significant magma body. First, seismic velocities show a low velocity layer consistent with a magmatic sill below depths of 15-20 km. This inference is corroborated by high electrical conductivity between 10km and 30km. This magma body, the so called Altiplano-Puna Magma Body (APMB) is the likely source of volcanic activity in the region. InSAR studies show that during the 1990s, the volcano experienced an average uplift of about 1 to 2 cm per year. The deformation is consistent with an expanding source at depth. Though the Uturuncu region exhibits high rates of crustal seismicity, any connection between the inflation and the seismicity is unclear. We investigate the root causes of these earthquakes using a temporary network of 33 seismic stations - part of the PLUTONS project. Our primary approach is based on hypocenter locations and magnitudes paired with correlation-based relative relocation techniques. We find a strong tendency toward earthquake swarms that cluster in space and time. These swarms often last a few days and consist of numerous earthquakes with similar source mechanisms. Most seismicity occurs in the top 10 kilometers of the crust and is characterized by well-defined phase arrivals and significant high frequency content. The frequency-magnitude relationship of this seismicity demonstrates b-values consistent with tectonic sources. There is a strong clustering of earthquakes around the Uturuncu edifice. Earthquakes elsewhere in the region align in bands striking northwest-southeast consistent with regional stresses.

  20. Water content in arc basaltic magma in the Northeast Japan and Izu arcs: an estimate from Ca/Na partitioning between plagioclase and melt

    NASA Astrophysics Data System (ADS)

    Ushioda, Masashi; Takahashi, Eiichi; Hamada, Morihisa; Suzuki, Toshihiro

    2014-12-01

    The variation in water content of arc basaltic magmas in the Northeast Japan arc and the Izu arc was estimated using a simple plagioclase phenocryst hygrometer. In order to construct a plagioclase phenocryst hygrometer optimized for arc basalt magmas, we have conducted high-pressure melting experiments of relatively primitive basalt from the Miyakejima volcano, a frontal-arc volcano in the Izu arc. As a result of the experiments, we found that the Ca/Na partition coefficient between plagioclase and hydrous basaltic melt increases linearly with an increase in H2O content in the melts. We then selected from literature geochemical data sets of relatively primitive basaltic rocks with no evidence of magma mixing and the most frequent Ca-rich plagioclase phenocrysts from 15 basaltic arc volcanoes including both frontal-arc and rear-arc volcanoes. In the 15 volcanoes studied, plagioclase phenocrysts of high anorthite content (An > 90) were commonly observed, whereas plagioclase phenocrysts in rear arc volcanoes usually had a lower anorthite content (90 > An > 80). In all volcanoes studied, the estimated H2O content of basaltic magma was at least 3 wt.% H2O or higher. The magmas of volcanoes located on the volcanic front have about 5 wt.% H2O in magma whereas those from the rear-arc side are slightly lower in H2O content.

  1. Wide Angle View of Arsia Mons Volcano

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Arsia Mons (above) is one of the largest volcanoes known. This shield volcano is part of an aligned trio known as the Tharsis Montes--the others are Pavonis Mons and Ascraeus Mons. Arsia Mons is rivaled only by Olympus Mons in terms of its volume. The summit of Arsia Mons is more than 9 kilometers (5.6 miles) higher than the surrounding plains. The crater--or caldera--at the volcano summit is approximately 110 km (68 mi) across. This view of Arsia Mons was taken by the red and blue wide angle cameras of the Mars Global Surveyor Mars Orbiter Camera (MOC) system. Bright water ice clouds (the whitish/bluish wisps) hang above the volcano--a common sight every martian afternoon in this region. Arsia Mons is located at 120o west longitude and 9o south latitude. Illumination is from the left.

  2. Halogen Oxide Measurements at Masaya Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Kern, C.; Vogel, L.; Sihler, H.; Rivera, C.; Strauch, W.; Galle, B.; Platt, U.

    2007-12-01

    Sulphur dioxide (SO2) and halogen oxide emissions were measured at Masaya Volcano in Nicaragua in April 2007 using differential optical absorption spectroscopy (DOAS). Next to passive DOAS measurements using scattered sunlight, an active long-path DOAS system was operated for several days with the light beam crossing the crater of the volcano. These measurements for the first time give an insight into the night-time halogen chemistry occurring at volcanoes. While the passive DOAS instruments measured sulphur dioxide (SO2) and bromine monoxide (BrO) in various viewing geometries and distances from the crater during daytime, the active instrument additionally allowed a quantification of chlorine monoxide (ClO) and chlorine dioxide (OClO), as well as being able to measure round-the-clock. The results of the field measurements will be presented and their implications for halogen chemistry at volcanoes will be discussed.

  3. Lahar hazards at Agua volcano, Guatemala

    USGS Publications Warehouse

    Schilling, S.P.; Vallance, J.W.; Matías, O.; Howell, M.M.

    2001-01-01

    At 3760 m, Agua volcano towers more than 3500 m above the Pacific coastal plain to the south and 2000 m above the Guatemalan highlands to the north. The volcano is within 5 to 10 kilometers (km) of Antigua, Guatemala and several other large towns situated on its northern apron. These towns have a combined population of nearly 100,000. It is within about 20 km of Escuintla (population, ca. 100,000) to the south. Though the volcano has not been active in historical time, or about the last 500 years, it has the potential to produce debris flows (watery flows of mud, rock, and debris—also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

  4. Radial anisotropy ambient noise tomography of volcanoes

    NASA Astrophysics Data System (ADS)

    Mordret, Aurélien; Rivet, Diane; Shapiro, Nikolai; Jaxybulatov, Kairly; Landès, Matthieu; Koulakov, Ivan; Sens-Schönfelder, Christoph

    2016-04-01

    The use of ambient seismic noise allows us to perform surface-wave tomography of targets which could hardly be imaged by other means. The frequencies involved (~ 0.5 - 20 s), somewhere in between active seismic and regular teleseismic frequency band, make possible the high resolution imaging of intermediate-size targets like volcanic edifices. Moreover, the joint inversion of Rayleigh and Love waves dispersion curves extracted from noise correlations allows us to invert for crustal radial anisotropy. We present here the two first studies of radial anisotropy on volcanoes by showing results from Lake Toba Caldera, a super-volcano in Indonesia, and from Piton de la Fournaise volcano, a hot-spot effusive volcano on the Réunion Island (Indian Ocean). We will see how radial anisotropy can be used to infer the main fabric within a magmatic system and, consequently, its dominant type of intrusion.

  5. A field guide to Newberry Volcano, Oregon

    USGS Publications Warehouse

    Jenson, Robert A.; Donnelly-Nolan, Julie M.; McKay, Daniele

    2009-01-01

    Newberry Volcano is located in central Oregon at the intersection of the Cascade Range and the High Lava Plains. Its lavas range in age from ca. 0.5 Ma to late Holocene. Erupted products range in composition from basalt through rhyolite and cover ~3000 km2. The most recent caldera-forming eruption occurred ~80,000 years ago. This trip will highlight a revised understanding of the volcano's history based on new detailed geologic work. Stops will also focus on evidence for ice and flooding on the volcano, as well as new studies of Holocene mafic eruptions. Newberry is one of the most accessible U.S. volcanoes, and this trip will visit a range of lava types and compositions including tholeiitic and calc-alkaline basalt flows, cinder cones, and rhyolitic domes and tuffs. Stops will include early distal basalts as well as the youngest intracaldera obsidian flow.

  6. Economic geology: Ore metals beneath volcanoes

    NASA Astrophysics Data System (ADS)

    Nadeau, Olivier

    2015-03-01

    Metals often accumulate in the crust beneath volcanoes. Laboratory experiments and observations reveal important roles for magmatic vapours and brines in transporting and concentrating the metals into deposits worth targeting for extraction.

  7. Lahar hazards at Mombacho Volcano, Nicaragua

    USGS Publications Warehouse

    Vallance, J.W.; Schilling, S.P.; Devoli, G.

    2001-01-01

    Mombacho volcano, at 1,350 meters, is situated on the shores of Lake Nicaragua and about 12 kilometers south of Granada, a city of about 90,000 inhabitants. Many more people live a few kilometers southeast of Granada in 'las Isletas de Granada and the nearby 'Peninsula de Aseses. These areas are formed of deposits of a large debris avalanche (a fast moving avalanche of rock and debris) from Mombacho. Several smaller towns with population, in the range of 5,000 to 12,000 inhabitants are to the northwest and the southwest of Mombacho volcano. Though the volcano has apparently not been active in historical time, or about the last 500 years, it has the potential to produce landslides and debris flows (watery flows of mud, rock, and debris -- also known as lahars when they occur on a volcano) that could inundate these nearby populated areas. -- Vallance, et.al., 2001

  8. Eruption of Alaska volcano breaks historic pattern

    USGS Publications Warehouse

    Larsen, Jessica; Neal, Christina A.; Webley, Peter; Freymueller, Jeff; Haney, Matthew; McNutt, Stephen; Schneider, David; Prejean, Stephanie; Schaefer, Janet; Wessels, Rick L.

    2009-01-01

    In the late morning of 12 July 2008, the Alaska Volcano Observatory (AVO) received an unexpected call from the U.S. Coast Guard, reporting an explosive volcanic eruption in the central Aleutians in the vicinity of Okmok volcano, a relatively young (~2000-year-old) caldera. The Coast Guard had received an emergency call requesting assistance from a family living at a cattle ranch on the flanks of the volcano, who reported loud "thunder," lightning, and noontime darkness due to ashfall. AVO staff immediately confirmed the report by observing a strong eruption signal recorded on the Okmok seismic network and the presence of a large dark ash cloud above Okmok in satellite imagery. Within 5 minutes of the call, AVO declared the volcano at aviation code red, signifying that a highly explosive, ash-rich eruption was under way.

  9. Major Martian Volcanoes from MOLA - Olympus Mons

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Two views of Olympus Mons, shown as topography draped over a Viking image mosaic. MOLA's regional topography has shown that this volcano sits off to the west of the main Tharsis rise rather than on its western flank. The topography also clearly shows the relationship between the volcano's scarp and massive aureole deposit that was produced by flank collapse. The vertical exaggeration is 10:1.

  10. Volcano Inflation prior to Gas Explosions at Semeru Volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Nishimura, T.; Iguchi, M.; Kawaguchi, R.; Surono, S.; Hendrasto, M.; Rosadi, U.

    2010-12-01

    Semeru volcano in east Java, Indonesia, is well known to exhibit small vulcanian eruptions at the summit crater. Such eruptive activity stopped on April 2009, but volcanic earthquakes started to occur in August and a lava dome was found in the summit crater on November. Since then, lava sometimes flows downward on the slope and small explosions emitting steams from active crater frequently occur every a few to a few tens of minutes. Since the explosions repeatedly occur with short intervals and the active crater is located close to the summit with an altitude of 3676m, the explosions are considered to originate from the gas (steams) from magma itself in the conduit and not to be caused by interactions of magma with the underground water. We installed a tiltmeter at the summit on March 2010 to study the volcanic eruption mechanisms. The tiltmeter (Pinnacle hybrid type, accuracy of measurement is 1 nrad ) was set at a depth of about 1 m around the summit about 500 m north from the active crater. The data stored every 1 s in the internal memory was uploaded every 6 hours by a small data logger with GPS time correction function. More than one thousand gas explosion events were observed for about 2 weeks. We analyze the tilt records as well as seismic signals recorded at stations of CVGHM, Indonesia. The tilt records clearly show uplift of the summit about 20 to 30 seconds before each explosion. Uplifts before large explosions reach to about 20 - 30 n rad, which is almost equivalent to the volume increase of about 100 m^3 beneath the crater. To examine the eruption magnitude dependence on the uplift, we classify the eruptions into five groups based on the amplitudes of seismograms associated with explosions. We stack the tilt records for these groups to reduce noises in the signals and to get general characteristics of the volcano inflations. The results show that the amplitudes of uplifts are almost proportional to the amplitudes of explosion earthquakes while the

  11. Evolution of large shield volcanoes on Venus

    NASA Technical Reports Server (NTRS)

    Herrick, Robert R.; Dufek, Josef; McGovern, Patrick J.

    2005-01-01

    We studied the geologic history, topographic expression, and gravity signature of 29 large Venusian shield volcanoes with similar morphologies in Magellan synthetic aperture radar imagery. While they appear similar in imagery, 16 have a domical topographic expression and 13 have a central depression. Typical dimensions for the central depression are 150 km wide and 500 m deep. The central depressions are probably not calderas resulting from collapse of a shallow magma chamber but instead are the result of a corona-like sagging of a previously domical volcano. The depressions all have some later volcanic filling. All but one of the central depression volcanoes have been post-dated by geologic features unrelated to the volcano, while most of the domical volcanoes are at the top of the stratigraphic column. Analysis of the gravity signatures in the spatial and spectral domains shows a strong correlation between the absence of post-dating features and the presence of dynamic support by an underlying plume. We infer that the formation of the central depressions occurred as a result of cessation of dynamic support. However, there are some domical volcanoes whose geologic histories and gravity signatures also indicate that they are extinct, so sagging of the central region apparently does not always occur when dynamic support is removed. We suggest that the thickness of the elastic lithosphere may be a factor in determining whether a central depression forms when dynamic support is removed, but the gravity data are of insufficient resolution to test this hypothesis with admittance methods.

  12. Influence of an ocean on the propagation of magmas within an oceanic basaltic shield volcano

    NASA Astrophysics Data System (ADS)

    Le Corvec, Nicolas; McGovern, Patrick

    2015-04-01

    Basaltic shield volcanoes are a common feature on Earth and mostly occur within oceans, forming volcanic islands (e.g. Hawaii (USA), Galapagos (Ecuador), and recently Niijima (Japan)). As the volcano grows it will reach and emerge from the water surface and continue to grow above it. The deformation affecting the volcanic edifice may be influenced by the presence of the water level. We investigate how the presence of an ocean affects the state of stress within a volcanic edifice and thus magma propagation and fault formation. Using COMSOL Multiphysics, axisymmetric elastic models of a volcanic edifice overlying an elastic lithosphere were created. The volcanic edifice (height of ~6000 m and radius of ~ 60 km) was built either instantaneously or iteratively by adding new layers of equivalent volume on top of each other. In the later process, the resulting stress and geometry from the one step is transferred to the next as initial conditions. Thus each new layer overlies a deformed and stressed model. The water load was modeled with a boundary condition at the surface of the model. In the case of an instantaneous volcano different water level were studied, for an iteratively growing volcano the water level was set up to 4000 m. We compared the deformation of the volcanic edifice and lithosphere and the stress orientation and magnitude in half-space and flexural models with the presence or not of an ocean. The preliminary results show 1- major differences in the resulting state of stress between an instantaneous and an iteratively built volcanic edifice, similar to the results of Galgana et al. (2011) and McGovern and Solomon (1993), respectively; 2- the presence of an ocean decreases the amount of flexural response, which decreases the magnitude of differential stress within the models; and 3- stress orientation within the volcano and lithosphere in also influence of an ocean. Those results provide new insights on the state of stress and deformation of oceanic

  13. Space robotics in Japan

    NASA Astrophysics Data System (ADS)

    Whittaker, William; Lowrie, James W.; McCain, Harry; Bejczy, Antal; Sheridan, Tom; Kanade, Takeo; Allen, Peter

    1994-03-01

    Japan has been one of the most successful countries in the world in the realm of terrestrial robot applications. The panel found that Japan has in place a broad base of robotics research and development, ranging from components to working systems for manufacturing, construction, and human service industries. From this base, Japan looks to the use of robotics in space applications and has funded work in space robotics since the mid-1980's. The Japanese are focusing on a clear image of what they hope to achieve through three objectives for the 1990's: developing long-reach manipulation for tending experiments on Space Station Freedom, capturing satellites using a free-flying manipulator, and surveying part of the moon with a mobile robot. This focus and a sound robotics infrastructure is enabling the young Japanese space program to develop relevant systems for extraterrestrial robotics applications.

  14. Space robotics in Japan

    NASA Technical Reports Server (NTRS)

    Whittaker, William; Lowrie, James W.; Mccain, Harry; Bejczy, Antal; Sheridan, Tom; Kanade, Takeo; Allen, Peter

    1994-01-01

    Japan has been one of the most successful countries in the world in the realm of terrestrial robot applications. The panel found that Japan has in place a broad base of robotics research and development, ranging from components to working systems for manufacturing, construction, and human service industries. From this base, Japan looks to the use of robotics in space applications and has funded work in space robotics since the mid-1980's. The Japanese are focusing on a clear image of what they hope to achieve through three objectives for the 1990's: developing long-reach manipulation for tending experiments on Space Station Freedom, capturing satellites using a free-flying manipulator, and surveying part of the moon with a mobile robot. This focus and a sound robotics infrastructure is enabling the young Japanese space program to develop relevant systems for extraterrestrial robotics applications.

  15. Cultural Astronomy in Japan

    NASA Astrophysics Data System (ADS)

    Renshaw, Steven L.

    While Japan is known more for its contributions to modern astronomy than its archaeoastronomical sites, there is still much about the culture's heritage that is of interest in the study of cultural astronomy. This case study provides an overview of historical considerations necessary to understand the place of astronomy in Japanese society as well as methodological considerations that highlight traditional approaches that have at times been a barrier to interdisciplinary research. Some specific areas of study in the cultural astronomy of Japan are discussed including examples of contemporary research based on interdisciplinary approaches. Japan provides a fascinating background for scholars who are willing to go beyond their curiosity for sites of alignment and approach the culture with a desire to place astronomical iconography in social context.

  16. Occupational asthma in Japan.

    PubMed

    Dobashi, Kunio

    2012-07-01

    Research into occupational asthma (OA) in Japan has been led by the Japanese Society of Occupational and Environmental Allergy. The first report about allergic OA identified konjac asthma. After that, many kinds of OA have been reported. Cases of some types of OA, such as konjac asthma and sea squirt asthma, have been dramatically reduced by the efforts of medical personnel. Recently, with the development of new technologies, chemical antigen-induced asthma has increased in Japan. Due to advances in anti-asthma medication, control by medical treatment tends to be emphasized and the search for causative antigens seems to be neglected. Furthermore, we do not have a Japanese guideline for diagnosis and management of OA. This article discusses the current state of OA in Japan. PMID:22872819

  17. Earthquakes - Volcanoes (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2013-04-01

    Earthquakes and volcanoes are caused by: 1)Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2)Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3)The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is

  18. Earthquakes - Volcanoes (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2015-04-01

    Earthquakes and volcanoes are caused by: 1) Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2) Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3) The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is

  19. EARTHQUAKES - VOLCANOES (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2014-05-01

    Earthquakes and volcanoes are caused by: 1)Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2)Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3)The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is

  20. An Admittance Survey of Large Volcanoes on Venus: Implications for Volcano Growth

    NASA Technical Reports Server (NTRS)

    Brian, A. W.; Smrekar, S. E.; Stofan, E. R.

    2004-01-01

    Estimates of the thickness of the venusian crust and elastic lithosphere are important in determining the rheological and thermal properties of Venus. These estimates offer insights into what conditions are needed for certain features, such as large volcanoes and coronae, to form. Lithospheric properties for much of the large volcano population on Venus are not well known. Previous studies of elastic thickness (Te) have concentrated on individual or small groups of edifices, or have used volcano models and fixed values of Te to match with observations of volcano morphologies. In addition, previous studies use different methods to estimate lithospheric parameters meaning it is difficult to compare their results. Following recent global studies of the admittance signatures exhibited by the venusian corona population, we performed a similar survey into large volcanoes in an effort to determine the range of lithospheric parameters shown by these features. This survey of the entire large volcano population used the same method throughout so that all estimates could be directly compared. By analysing a large number of edifices and comparing our results to observations of their morphology and models of volcano formation, we can help determine the controlling parameters that govern volcano growth on Venus.

  1. Interagency collaboration on an active volcano: a case study at Hawai‘i Volcanoes National Park

    USGS Publications Warehouse

    Kauahikaua, James P.; Orlando, Cindy

    2014-01-01

    Because Kilauea and Mauna Loa are included within the National Park, there is a natural intersection of missions for the National Park Service (NPS) and the U.S. Geological Survey (USGS). HAVO staff and the USGS Hawaiian Volcano Observatory scientists have worked closely together to monitor and forecast multiple eruptions from each of these volcanoes since HAVO’s founding in 1916.

  2. Spreading and collapse of big basaltic volcanoes

    NASA Astrophysics Data System (ADS)

    Puglisi, Giuseppe; Bonforte, Alessandro; Guglielmino, Francesco; Peltier, Aline; Poland, Michael

    2016-04-01

    Among the different types of volcanoes, basaltic ones usually form the most voluminous edifices. Because volcanoes are growing on a pre-existing landscape, the geologic and structural framework of the basement (and earlier volcanic landforms) influences the stress regime, seismicity, and volcanic activity. Conversely, the masses of these volcanoes introduce a morphological anomaly that affects neighboring areas. Growth of a volcano disturbs the tectonic framework of the region, clamps and unclamps existing faults (some of which may be reactivated by the new stress field), and deforms the substratum. A volcano's weight on its basement can trigger edifice spreading and collapse that can affect populated areas even at significant distance. Volcano instability can also be driven by slow tectonic deformation and magmatic intrusion. The manifestations of instability span a range of temporal and spatial scales, ranging from slow creep on individual faults to large earthquakes affecting a broad area. In the frame of MED-SVU project, our work aims to investigate the relation between basement setting and volcanic activity and stability at three Supersite volcanoes: Etna (Sicily, Italy), Kilauea (Island of Hawaii, USA) and Piton de la Fournaise (La Reunion Island, France). These volcanoes host frequent eruptive activity (effusive and explosive) and share common features indicating lateral spreading and collapse, yet they are characterized by different morphologies, dimensions, and tectonic frameworks. For instance, the basaltic ocean island volcanoes of Kilauea and Piton de la Fournaise are near the active ends of long hotspot chains while Mt. Etna has developed at junction along a convergent margin between the African and Eurasian plates and a passive margin separating the oceanic Ionian crust from the African continental crust. Magma supply and plate velocity also differ in the three settings, as to the sizes of the edifices and the extents of their rift zones. These

  3. Nyiragongo Volcano before the Eruption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nyiragongo is an active stratovolcano situated on the Eastern African Rift; it is part of Africa's Virunga Volcanic Chain. In a massive eruption that occurred on January 17, 2002, Nyiragongo sent a vast plume of smoke and ash skyward, and three swifly-moving rivers of lava streaming down its western and eastern flanks. Previous lava flows from Nyiragongo have been observed moving at speeds of up to 40 miles per hour (60 kph). The lava flows from the January 17 eruption destroyed more than 14 villages in the surrounding countryside, forcing tens of thousands to flee into the neighboring country of Rwanda. Within one day the lava ran to the city of Goma, situated on the northern shore of Lake Kivu about 12 miles (19 km) south of Nyiragongo. The lava cut a 200 foot (60 meter) wide swath right through Goma, setting off many fires, as it ran into Lake Kivu. Goma, the most heavily populated city in eastern Democratic Republic of Congo, is home to about 400,000 people. Most of these citizens were forced to flee, while many have begun to return to their homes only to find their homes destroyed. This true-color scene was captured by the Enhanced Thematic Mapper Plus (ETM+), flying aboard the Landsat 7 satellite, on December 11, 2001, just over a month before the most recent eruption. Nyiragongo's large crater is clearly visible in the image. As recently as June 1994, there was a large lava lake in the volcano's crater which had since solidified. The larger Nyamuragira Volcano is located roughly 13 miles (21 km) to the north of Nyiragongo. Nyamuragira last erupted in February and March 2001. That eruption was also marked by columns of erupted ash and long fluid lava flows, some of which are apparent in the image as dark greyish swaths radiating away from Nyamuragira. Both peaks are also notorious for releasing large amounts of sulfur dioxide, which presents another health hazard to people and animals living in close proximity. Image by Robert Simmon, based on data supplied

  4. "Hands on" Japan.

    ERIC Educational Resources Information Center

    Borries, Richard

    Cultural learning kits designed by Evansville, Indiana teachers, supervisors, and community advisory groups were compiled to provide information about Japan to community organizations and students. This document provides a key to the contents of the kits. The kits contain teaching materials and information about food, school materials, language…

  5. Advanced composites in Japan

    NASA Technical Reports Server (NTRS)

    Diefendorf, R. Judd; Hillig, William G.; Grisaffe, Salvatore J.; Pipes, R. Byron; Perepezko, John H.; Sheehan, James E.

    1994-01-01

    The JTEC Panel on Advanced Composites surveyed the status and future directions of Japanese high-performance ceramic and carbon fibers and their composites in metal, intermetallic, ceramic, and carbon matrices. Because of a strong carbon and fiber industry, Japan is the leader in carbon fiber technology. Japan has initiated an oxidation-resistant carbon/carbon composite program. With its outstanding technical base in carbon technology, Japan should be able to match present technology in the U.S. and introduce lower-cost manufacturing methods. However, the panel did not see any innovative approaches to oxidation protection. Ceramic and especially intermetallic matrix composites were not yet receiving much attention at the time of the panel's visit. There was a high level of monolithic ceramic research and development activity. High temperature monolithic intermetallic research was just starting, but notable products in titanium aluminides had already appeared. Matrixless ceramic composites was one novel approach noted. Technologies for high temperature composites fabrication existed, but large numbers of panels or parts had not been produced. The Japanese have selected aerospace as an important future industry. Because materials are an enabling technology for a strong aerospace industry, Japan initiated an ambitious long-term program to develop high temperature composites. Although just starting, its progress should be closely monitored in the U.S.

  6. Japan's electronic packaging technologies

    NASA Technical Reports Server (NTRS)

    Tummala, Rao R.; Pecht, Michael

    1995-01-01

    The JTEC panel found Japan to have significant leadership over the United States in the strategic area of electronic packaging. Many technologies and products once considered the 'heart and soul' of U.S. industry have been lost over the past decades to Japan and other Asian countries. The loss of consumer electronics technologies and products is the most notable of these losses, because electronics is the United States' largest employment sector and is critical for growth businesses in consumer products, computers, automobiles, aerospace, and telecommunications. In the past there was a distinction between consumer and industrial product technologies. While Japan concentrated on the consumer market, the United States dominated the industrial sector. No such distinction is anticipated in the future; the consumer-oriented technologies Japan has dominated are expected to characterize both domains. The future of U.S. competitiveness will, therefore, depend on the ability of the United States to rebuild its technological capabilities in the area of portable electronic packaging.

  7. Dutch surgery in Japan.

    PubMed

    van Gulik, Thomas M; Nimura, Yuji

    2005-01-01

    An isolation policy was adopted in feudal Japan from 1639 to 1853 owing to the fear of foreign influence. During those 200 years of isolation, all foreigners were withheld from the country with the exception of the Dutch, who were permitted to establish a trading post on a small island in the Bay of Nagasaki, called Decima. Western culture and science reached the Japanese exclusively through the Dutch on Decima. Health care on Decima was provided by Dutch barber-surgeons, who introduced Western surgical practice in Japan. Official interpreters were the only Japanese allowed on Decima. It was from among these interpreters that the first Japanese surgeons arose who, having mastered the Dutch language, translated several Dutch anatomic and surgical texts. Genpaku Sugita translated a Dutch anatomy textbook into Japanese, which was completed in 1774. This book, entitled Kaitai Shinsho [New Book on Anatomy], was the first Western scientific monograph to be translated entirely into Japanese. Several Dutch surgical schools were founded through which Dutch surgery, known in Japan as "surgery of the red-haired" was propagated. According to the custom of the surgical guilds in Holland, certificates were granted to Japanese apprentices who had completed their training in Dutch surgery. About 60 Dutch surgeons had served on Decima up to 1850, providing the basis for surgery to develop in Japan. Among them, Philipp Franz von Siebold was an exceptional scholar who also had a great impact in making Japanese culture known to the Western world. PMID:15599736

  8. Political Corruption in Japan.

    ERIC Educational Resources Information Center

    Reed, Steven R.; And Others

    1996-01-01

    Provides an overview of political corruption and its place in Japanese culture and society. Discusses recent scandals and efforts at political reform. These efforts are moving Japan from a "boss-patronage" system to a "civic-culture." Includes a table of post-war Japanese prime ministers and corruption scandals. (MJP)

  9. [Films: China and Japan].

    ERIC Educational Resources Information Center

    Gumport, Roberta H.

    The history of filmmaking in China and Japan and film usage in teaching are considered in this document. Pointing out how films describe historical context and culture, the document also describes various techniques of film making. Films in China were heavily influenced by western models and have tended to be tools of the power structure, as…

  10. Photovoltaics in Japan

    NASA Technical Reports Server (NTRS)

    Shimada, K.

    1985-01-01

    Report surveys status of research and development on photovoltaics in Japan. Report based on literature searches, private communications, and visits by author to Japanese facilities. Included in survey are Sunshine Project, national program to develop energy sources; industrial development at private firms; and work at academic institutions.

  11. Japan's electronic packaging technologies

    NASA Astrophysics Data System (ADS)

    Tummala, Rao R.; Pecht, Michael

    1995-02-01

    The JTEC panel found Japan to have significant leadership over the United States in the strategic area of electronic packaging. Many technologies and products once considered the 'heart and soul' of U.S. industry have been lost over the past decades to Japan and other Asian countries. The loss of consumer electronics technologies and products is the most notable of these losses, because electronics is the United States' largest employment sector and is critical for growth businesses in consumer products, computers, automobiles, aerospace, and telecommunications. In the past there was a distinction between consumer and industrial product technologies. While Japan concentrated on the consumer market, the United States dominated the industrial sector. No such distinction is anticipated in the future; the consumer-oriented technologies Japan has dominated are expected to characterize both domains. The future of U.S. competitiveness will, therefore, depend on the ability of the United States to rebuild its technological capabilities in the area of portable electronic packaging.

  12. Country Profiles. Japan.

    ERIC Educational Resources Information Center

    Muramatsu, Minoru

    This occasional paper on Japan is one of a series setting forth the nature, scope, and accomplishments of population activities in specified countries. Here, an overview is given of population characteristics and growth patterns, the relationship of population growth to socioeconomic development, and the history of population concerns and…

  13. Japan: Tsunami Flooding

    Atmospheric Science Data Center

    2013-04-16

    ... of 41 kilometers (25 miles) by 89 kilometers (55 miles). Flooding extending about 2 kilometers (1.2 miles) inland is visible just north ... March 18, 2005 and March 19, 2011 - Before and after tsunami flooding along Japan's eastern coast. project:  MISR ...

  14. Language Testing in Japan.

    ERIC Educational Resources Information Center

    Brown, James Dean, Ed.; Yamashita, Sayoko Okada, Ed.

    Papers on second language testing in Japan include: "Differences Between Norm-Referenced and Criterion-Referenced Tests" (James Dean Brown); "Criterion-Referenced Test Construction and Evaluation" (Dale T. Griffe); "Behavioral Learning Objectives as an Evaluation Tool" (Judith A. Johnson); "Developing Norm- Referenced Tests for Program-Level…

  15. Nuclear Power in Japan.

    ERIC Educational Resources Information Center

    Powell, John W.

    1983-01-01

    Energy consumption in Japan has grown at a faster rate than in any other major industrial country. To maintain continued prosperity, the government has embarked on a crash program for nuclear power. Current progress and issues/reactions to the plan are discussed. (JN)

  16. Hilarionite, Fe{2/3+}(SO4)(AsO4)(OH) · 6H2O, a new supergene mineral from Lavrion, Greece

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Chukanov, N. V.; Yapaskurt, V. O.; Rusakov, V. S.; Belakovsky, D. I.; Turchkova, A. G.; Voudouris, P.; Magganas, A.; Katerinopoulos, A.

    2014-12-01

    A new mineral, hilarionite, ideally Fe{2/3+} (SO4)(AsO4)(OH) · 6H2O, has been found in the Hilarion Mine, Agios Konstantinos, Kamariza, Lavrion district, Attiki Prefecture, Greece. It was formed in the oxidation zone of a sulfide-rich orebody in association with goethite, gypsum, bukovskyite, jarosite, melanterite, chalcanthite, allophane, and azurite. Hilarionite occurs as light green (typically with an olive or grayish tint) to light yellowish green spherulites (up to 1 mm in size) and bunches of prismatic to acicular "individuals" up to 0.5 mm long that are in fact near-parallel or divergent aggregates of very thin, curved fibers up to 0.3 mm long and usually lesser than 2 μm thick. The luster is silky to vitreous. The Mohs' hardness is ca. 2. Hilarionite is ductile, its "individuals" are flexible and inelastic; fracture is uneven or splintery. D(meas) = 2.40(5), D(calc) = 2.486 g/cm3. IR spectrum shows the presence of arsenate and sulfate groups and H2O molecules in significant amounts. The Mössbauer spectrum indicates the presence of Fe3+ at two six-fold coordinated sites and the absence of Fe2+. Hilarionite is optically biaxial (+), α = 1.575(2), γ = 1.64(2), 2 V is large. The chemical composition (electron microprobe, average of 7 point analyses; H2O determined by modified Penfield method) is as follows, wt %: 0.03 MnO, 0.18 CuO, 0.17 ZnO, 33.83 Fe2O3, 0.22 P2O5, 18.92 As2O5, 22.19 SO3, 26.3 H2O, total is 101.82%. The empirical formula calculated on the basis of 15 O is: (Fe{1.90/3+}Cu0.01Zn0.01)Σ1.92[(SO4)1.24(AsO4)0.74(PO4)0.01]Σ1.99(OH)1.01 · 6.03H2O. The X-ray powder diffraction data show close structural relationship of hilarionite and kaňkite, Fe{2/3+}(AsO4)2 · 7H2O. Hilarionite is monoclinic, space group C2/ m, Cm or C2, a = 18.53(4), b = 17.43(3), c = 7.56(1) Å, β = 94.06(15)°, V = 2436(3) Å3, Z = 8. The strongest reflections in the X-ray powder diffraction pattern ( d, Å- I[ hkl]) are: 12.66-100[110], , 5.00-10[22l], , 4

  17. Eruption cyclicity at silicic volcanoes potentially caused by magmatic gas waves

    NASA Astrophysics Data System (ADS)

    Michaut, Chloé; Ricard, Yanick; Bercovici, David; Sparks, R. Steve J.

    2013-10-01

    Eruptions at active silicic volcanoes are often cyclical. For example, at the Soufrière Hills volcano in Montserrat, Mount Pinatubo in the Philippines, and Sakurajima in Japan, episodes of intense activity alternate with repose intervals over periods between several hours and a day. Abrupt changes in eruption rates have been explained with the motion of a plug of magma that alternatively sticks or slides along the wall of the volcanic conduit. However, it is unclear how the static friction that prevents the plug from sliding is periodically overcome. Here we use two-phase flow equations to model a gas-rich, viscous magma ascending through a volcanic conduit. Our analyses indicate that magma compaction yields ascending waves comprised of low- and high-porosity bands. However, magma ascent to lower pressures also causes gas expansion. We find that the competition between magma compaction and gas expansion naturally selects pressurized gas waves with specific periods. At the surface, these waves can induce cyclical eruptive behaviour with periods between 1 and 100 hours, which compares well to the observations from Soufrière Hills, Mount Pinatubo and Sakurajima. We find that the period is insensitive to volcano structure, but increases weakly with magma viscosity. We conclude that observations of a shift to a longer eruption cycle imply an increase in magma viscosity and thereby enhanced volcanic hazard.

  18. 4-D noise-based seismology at volcanoes: Ongoing efforts and perspectives

    NASA Astrophysics Data System (ADS)

    Brenguier, Florent; Rivet, Diane; Obermann, Anne; Nakata, Nori; Boué, Pierre; Lecocq, Thomas; Campillo, Michel; Shapiro, Nikolai

    2016-07-01

    Monitoring magma pressure buildup at depth and transport to surface is a key point for improving volcanic eruption prediction. Seismic waves, through their velocity dependence to stress perturbations, can provide crucial information on the temporal evolution of the mechanical properties of volcanic edifices. In this article, we review past and ongoing efforts for extracting accurate information of temporal changes of seismic velocities at volcanoes continuously in time using records of ambient seismic noise. We will first introduce the general methodology for retrieving accurate seismic velocity changes from seismic noise records and discuss the origin of seismic velocity temporal changes in rocks. We will then discuss in a second part how noise-based monitoring can improve our knowledge about magmatic activity at a long (years) to a short (days) time scale taking example from Piton de la Fournaise volcano (La Réunion). We will also mention ongoing efforts for operational noise-based seismic monitoring on volcanoes. Further, we will discuss perspectives for improving the spatial localization of detected velocity changes at depth with a special focus on the use of dense seismic arrays. In the last part, we will finally explore the complex response of volcanic regions to seismic shaking with an example from Japan and show how imaging seismic velocity susceptibility allows characterizing the state of pressurized fluids in volcanic regions.

  19. Lifelong Learning Facilities in Japan.

    ERIC Educational Resources Information Center

    Hirai, Akishige

    1997-01-01

    Examines Japan's educational system and the role of national policy and local government in fostering lifelong learning. Reasons why Japan is building a lifelong learning society are examined, as are the opportunities available in Japan for learning beyond traditional education, the national and local government's role, access to facilities,…

  20. Globalization and Education in Japan

    ERIC Educational Resources Information Center

    Ohkura, Kentaro; Shibata, Masako

    2009-01-01

    In this paper, the authors contend that globalization in Japan is the gradual process in which Japan's positioning of "self" within international relations, which had formerly been dominated by the West, has changed. Accordingly, Japan's relationships with the West and the rest of the world, for example, Asia, have also been reviewed and modified.…

  1. Effects of Volcanoes on the Natural Environment

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, Peter J.

    2005-01-01

    The primary focus of this project has been on the development of techniques to study the thermal and gas output of volcanoes, and to explore our options for the collection of vegetation and soil data to enable us to assess the impact of this volcanic activity on the environment. We originally selected several volcanoes that have persistent gas emissions and/or magma production. The investigation took an integrated look at the environmental effects of a volcano. Through their persistent activity, basaltic volcanoes such as Kilauea (Hawaii) and Masaya (Nicaragua) contribute significant amounts of sulfur dioxide and other gases to the lower atmosphere. Although primarily local rather than regional in its impact, the continuous nature of these eruptions means that they can have a major impact on the troposphere for years to decades. Since mid-1986, Kilauea has emitted about 2,000 tonnes of sulfur dioxide per day, while between 1995 and 2000 Masaya has emotted about 1,000 to 1,500 tonnes per day (Duffel1 et al., 2001; Delmelle et al., 2002; Sutton and Elias, 2002). These emissions have a significant effect on the local environment. The volcanic smog ("vog" ) that is produced affects the health of local residents, impacts the local ecology via acid rain deposition and the generation of acidic soils, and is a concern to local air traffic due to reduced visibility. Much of the work that was conducted under this NASA project was focused on the development of field validation techniques of volcano degassing and thermal output that could then be correlated with satellite observations. In this way, we strove to develop methods by which not only our study volcanoes, but also volcanoes in general worldwide (Wright and Flynn, 2004; Wright et al., 2004). Thus volcanoes could be routinely monitored for their effects on the environment. The selected volcanoes were: Kilauea (Hawaii; 19.425 N, 155.292 W); Masaya (Nicaragua; 11.984 N, 86.161 W); and Pods (Costa Rica; 10.2OoN, 84.233 W).

  2. Seismic unrest at Katla Volcano- southern Iceland

    NASA Astrophysics Data System (ADS)

    jeddi, zeinab; Tryggvason, Ari; Gudmundsson, Olafur; Bödvarsson, Reynir; SIL Seismology Group

    2014-05-01

    Katla volcano is located on the propagating Eastern Volcanic Zone (EVZ) in South Iceland. It is located beneath Mýrdalsjökull ice-cap which covers an area of almost 600 km2, comprising the summit caldera and the eruption vents. 20 eruptions between 930 and 1918 with intervals of 13-95 years are documented at Katla which is one of the most active subglacial volcanoes in Iceland. Eruptions at Katla are mainly explosive due to the subglacial mode of extrusion and produce high eruption columns and catastrophic melt water floods (jökulhlaups). The present long Volcanic repose (almost 96 years) at Katla, the general unrest since 1955, and the 2010 eruption of the neighbouring Eyjafjallajökull volcano has prompted concerns among geoscientists about an imminent eruption. Thus, the volcano has been densely monitored by seismologists and volcanologists. The seismology group of Uppsala University as a partner in the Volcano Anatomy (VA) project in collaboration with the University of Iceland and the Icelandic Meteorological Office (IMO) installed 9 temporary seismic stations on and around the Mýrdalsjökull glacier in 2011. Another 10 permanent seismic stations are operated by IMO around Katla. The project's data collection is now finished and temporary stations were pulled down in August 2013. According to seismicity maps of the whole recording period, thousands of microearthquakes have occurred within the caldera region. At least three different source areas are active in Katla: the caldera region, the western Godaland region and a small cluster at the southern rim of Mýrdalsjökull near the glacial stream of Hafursarjökull. Seismicity in the southern flank has basically started after June 2011. The caldera events are mainly volcano-tectonic, while western and southern events are mostly long period (lp) and can be related to glacial or magmatic movement. One motivation of the VA Katla project is to better understand the physical mechanism of these lp events. Changes

  3. Nature of the Moho in Japan and Kamchatka

    NASA Astrophysics Data System (ADS)

    Iwasaki, Takaya; Levin, Vadim; Nikulin, Alex; Iidaka, Takashi

    2013-04-01

    Japan Arc. The Moho and uppermost mantle structures beneath the southern part of the Kamchatka have a lot of similarities to those beneath the NE Japan Arc. Earlier DSS investigations and converted wave analyses show that Moho is situated at a depth of 38-40 km along the east coast of Kamchatka, that is beneath the volcanic front, but decreases to about 32 km near the west coast. Moho depth values based on modern receiver function methodology are also ranging from 31 to over 38 km. Moho is a fairly simple boundary under the western coast of Kamchatka, while in the Central Kamchatka Depression and especially along the eastern coast it is likely gradational. Uppermost mantle material beneath the Moho is complex, with additional impedance contrasts that are likely anisotropic in their properties being present under the entire Kamchatka peninsula. The dominant anisotorpy-inducing fabric varies from site to site along the west coast, but is almost universally trench-normal along the east coast. The seismic velocities beneath Kamchatka are very low (7.4-7.8 km/s for P-wave and 4.1-4.2 km/s for S wave). Also, gradual structural change is recognized around the Moho beneath the active volcanoes. These features are quite similar to those in NE Japan Arc.

  4. Volcanoes and volcanic provinces - Martian western hemisphere

    NASA Technical Reports Server (NTRS)

    Scott, D. H.

    1982-01-01

    The recognition of some Martian landforms as volcanoes is based on their morphology and geologic setting. Other structures, however, may exhibit classic identifying features to a varying or a less degree; these may be only considered provisionally as having a volcanic origin. Regional geologic mapping of the western hemisphere of Mars from Viking images has revealed many more probable volcanoes and volcanotectonic features than were recognized on Mariner 9 pictures. These abundant volcanoes have been assigned to several distinct provinces on the basis of their areal distribution. Although the Olympus-Tharsis region remains as the principle center of volcanism on Mars, four other important provinces are now also recognized: the lowland plains, Tempe Terra plateau, southern highlands (in the Phaethontis and Thaumasia quadrangles), and a probable ignimbrite province, situated along the highland-lowland boundary in Amazonis Planitia. Volcanoes in any one province vary in morphlogy, size, and age, but volcanoes in each province tend to have common characteristics that distinguish that particular group.

  5. Gravity model studies of Newberry Volcano, Oregon

    SciTech Connect

    Gettings, M.E.; Griscom, A.

    1988-09-10

    Newberry, Volcano, a large Quaternary volcano located about 60 km east of the axis of the High Cascades volcanoes in central Oregon, has a coincident positive residual gravity anomaly of about 12 mGals. Model calculations of the gravity anomaly field suggest that the volcano is underlain by an intrusive complex of mafic composition of about 20-km diameter and 2-km thickness, at depths above 4 km below sea level. However, uplifted basement in a northwest trending ridge may form part of the underlying excess mass, thus reducing the volume of the subvolcanic intrusive. A ring dike of mafic composition is inferred to intrude to near-surface levels along the caldera ring fractures, and low-density fill of the caldera floor probably has a thickness of 0.7--0.9 km. The gravity anomaly attributable to the volcano is reduced to the east across a north-northwest trending gravity anomaly gradient through Newberry caldera and suggests that normal, perhaps extensional, faulting has occurred subsequent to caldera formation and may have controlled the location of some late-stage basaltic and rhyolitic eruptions. Significant amounts of felsic intrusive material may exist above the mafic intrusive zone but cannot be resolved by the gravity data.

  6. Interferometric Synthetic Aperture radar studies of Alaska volcanoes

    USGS Publications Warehouse

    Lu, Zhong; Wicks, Charles W., Jr.; Dzurisin, Daniel; Power, John A.; Thatcher, Wayne R.; Masterlark, Timothy

    2003-01-01

    In this article, we summarize our recent InSAR studies of 13 Alaska volcanoes, including New Trident, Okmok, Akutan, Kiska, Augustine, Westdahl, Peulik, Makushin, Seguam, Shishaldin, Pavlof, Cleveland, and Korovin volcanoes.

  7. Volcanoes in the Classroom--an Explosive Learning Experience.

    ERIC Educational Resources Information Center

    Thompson, Susan A.; Thompson, Keith S.

    1996-01-01

    Presents a unit on volcanoes for third- and fourth-grade students. Includes demonstrations; video presentations; building a volcano model; and inviting a scientist, preferably a vulcanologist, to share his or her expertise with students. (JRH)

  8. Long- and short-term triggering and modulation of mud volcano eruptions by earthquakes

    NASA Astrophysics Data System (ADS)

    Bonini, Marco; Rudolph, Maxwell L.; Manga, Michael

    2016-03-01

    Earthquakes can trigger the eruption of mud. We use eruptions in Azerbaijan, Italy, Romania, Japan, Andaman Islands, Pakistan, Taiwan, Indonesia, and California to probe the nature of stress changes that induce new eruptions and modulate ongoing eruptions. Dynamic stresses produced by earthquakes are usually inferred to be the dominant triggering mechanism; however static stress changes acting on the feeder systems of mud volcanoes may also play a role. In Azerbaijan, eruptions within 2-10 fault lengths from the epicenter are favored in the year following earthquakes where the static stress changes cause compression of the mud source and unclamp feeder dikes. In Romania, Taiwan, and some Italian sites, increased activity is also favored where the static stress changes act to unclamp feeder dikes, but responses occur within days. The eruption in the Andaman Islands, and those of the Niikappu mud volcanoes, Japan are better correlated with amplitude of dynamic stresses produced by seismic waves. Similarly, a new island that emerged off the coast of Pakistan in 2013 was likely triggered by dynamic stresses, enhanced by directivity. At the southern end of the Salton Sea, California earthquakes increase the gas flux at small mud volcanoes. Responses are best correlated with dynamic stresses. The comparison of responses in these nine settings indicates that dynamic stresses are most often correlated with triggering, although permanent stress changes as small as, and possibly smaller than, 0.1 bar may be sufficient to also influence eruptions. Unclamping stresses with magnitude similar to Earth tides (0.01 bar) persist over time and may play a role in triggering delayed responses. Unclamping stresses may be important contributors to short-term triggering only if they exceed 0.1-1 bar.

  9. Rapid microwave synthesis of the iron arsenides NdFeAsO and NdFe{sub 0.9}Co{sub 0.1}AsO

    SciTech Connect

    Muir, Sean W.; Rachdi, Omar D.; Subramanian, M.A.

    2012-03-15

    Graphical abstract: For the first time, a rapid method for synthesizing NdFeAsO and NdFe{sub 0.9}Co{sub 0.1}AsO is reported. This method uses 2.45 GHz microwave radiation and an additional microwave susceptor to drive the reaction. The superconducting properties NdFe{sub 0.9}Co{sub 0.1}AsO of microwave synthesized materials match well with those reported previously. Highlights: Black-Right-Pointing-Pointer Microwave assisted solid state synthesis of NdFeAsO and NdFe{sub 0.9}Co{sub 0.1}AsO is reported. Black-Right-Pointing-Pointer Synthesis of high quality samples is achieved after 50 min microwave exposure. Black-Right-Pointing-Pointer Physical properties of microwave samples match those prepared conventionally. -- Abstract: The future of iron pnictide superconductors in technology is still undecided. While these materials are now known to possess relatively high critical temperatures and critical magnetic fields, processing methods for these superconductors are still in the development stage. Recently we have been investigating possible ways to speed up the synthetic process for obtaining polycrystalline iron arsenide superconductors and other transition metal pnictides. Here we report the synthesis of NdFeAsO and NdFe{sub 0.9}Co{sub 0.1}AsO in less than 1 h total exposure to microwave radiation using an additional microwave susceptor to surround the reaction ampoule. Structure and property measurements reveal the samples to be of high quality and superconducting when Co doped.

  10. Nyiragongo volcano, Congo, Perspective View with Lava SRTM / ASTER / Landsat

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Nyiragongo volcano in the Congo erupted on January 17, 2002, and subsequently sent streams of lava into the city of Goma on the north shore of Lake Kivu. More than 100 people were killed, more than 12,000 homes were destroyed, and hundreds of thousands were forced to flee the broader community of nearly half a million people. This computer-generated visualization combines a Landsat satellite image and an elevation model from the Shuttle Radar Topography Mission (SRTM) to provide a view of both the volcano and the city of Goma, looking slightly east of north. Additionally, image data from the Advanced Spaceborne Thermal Emission and reflection Radiometer (ASTER) on NASA's Terra satellite were used to supply a partial map of the recent lava flows (red), including a complete mapping of their intrusion into Goma as of January 28, 2002. Lava is also apparent within the volcanic crater and at a few other locations. Thick (but broken) cloud cover during the ASTER image acquisition prevented a complete mapping of the lava distribution, but future image acquisitions should complete the mapping.

    Nyiragongo is the steep volcano on the right, Lake Kivu is in the foreground, and the city of Goma has a light pink speckled appearance along the shoreline. Nyiragongo peaks at about 3,470 meters (11,380 feet) elevation and reaches almost exactly 2,000 meters (6,560 feet) above Lake Kivu. The shorter but broader Nyamuragira volcano appears in the left background. Topographic expression has been exaggerated vertically by a factor of 1.5 for this visualization.

    Goma, Lake Kivu, Nyiragongo, Nyamuragira and other nearby volcanoes sit within the East African Rift Valley, a zone where tectonic processes are cracking, stretching, and lowering the Earth's crust. Volcanic activity is common here, and older but geologically recent lava flows (magenta in this depiction) are particularly apparent on the flanks of the Nyamuragira volcano.

    The Landsat image used here was acquired

  11. Kilauea volcano eruption seen from orbit

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The STS-51 crew had a clear view of the erupting Kilauea volcano during the early morning pass over the Hawaiian islands. Kilauea, on the southwest side of the island of Hawaii, has been erupting almost continuously since January, 1983. Kilauea's summit caldera, with the smaller Halemaumau crater nestled within, is highlighted in the early morning sun (just above the center of the picture). The lava flows which covered roads and subdivisions in 1983-90 can be seen as dark flows to the east (toward the upper right) of the steam plumes on this photo. The summit crater and lava flows of Mauna Loa volcano make up the left side of the photo. Features like the Volcano House and Kilauea Visitor Center on the edge of the caldera, the small subdivisions east of the summit, Ola's Rain Forest north of the summit, and agricultural land along the coast are easily identified.

  12. Infrared and Raman spectroscopic characterizations on new Fe sulphoarsenate hilarionite (Fe2((III))(SO4)(AsO4)(OH)·6H2O): Implications for arsenic mineralogy in supergene environment of mine area.

    PubMed

    Liu, Jing; He, LiLe; Dong, Faqin; Frost, Ray L

    2017-01-01

    Hilarionite (Fe2 (SO4)(AsO4)(OH)·6H2O) is a new Fe sulphoarsenates mineral, which recently is found in the famous Lavrion ore district, Atliki Prefecture, Greece. The spectroscopic study of hilarionite enriches the data of arsenic mineralogy in supergene environment of a mine area. The infrared and Raman means are used to characterize the molecular structure of this mineral. The IR bands at 875 and 905cm(-1) are assigned to the antisymmetric stretching vibrations of AsO4(3-). The IR bands at 1021, 1086 and 1136cm(-1) correspond to the possible antisymmetric and symmetric stretching vibrations of SO4(2-). The Raman bands at 807, 843 and 875cm(-1) clearly show that arsenate components in the mineral structure, which are assigned to the symmetric stretching vibrations (ν1) of AsO4(3-) (807 and 843cm(-1)) and the antisymmetric vibration (ν3) (875cm(-1)). IR bands provide more sulfate information than Raman, which can be used as the basis to distinguish hilarionite from kaňkite. The powder XRD data shows that hilarionite has obvious differences with the mineral structure of kaňkite. The thermoanalysis and SEM-EDX results show that hilarionite has more sulfate than arsenate. PMID:27391313

  13. The mineral tooeleite Fe6(AsO3)4SO4(OH)4ṡ4H2O - An infrared and Raman spectroscopic study-environmental implications for arsenic remediation

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Cheng, Hongfei; Frost, Ray L.; Dong, Faqing

    2013-02-01

    The mineral tooeleite Fe6(AsO3)4SO4(OH)4ṡ4H2O is secondary ferric arsenite sulphate mineral which has environmental significance for arsenic remediation because of its high stability in the regolith. The mineral has been studied by X-ray diffraction (XRD), infrared (IR) and Raman spectroscopy. The XRD result indicates tooeleite can form more crystalline solids in an acid environment than in an alkaline environment. Infrared spectroscopy identifies moderately intense band at 773 cm-1 assigned to AsO33- symmetric stretching vibration. Raman spectroscopy identifies three bands at 803, 758 and 661 cm-1 assigned to the symmetric and antisymmetric stretching vibrations of AsO33- and As-OH stretching vibration respectively. In addition, the infrared bands observed at 1116, 1040, 1090, 981 and 616 cm-1, are assigned to the ν3, ν1 and ν4 modes of SO42-. The same bands are observed at 1287, 1085, 983 and 604 cm-1 in the Raman spectrum. As3d band at binding energy of 44.05 eV in XPS confirms arsenic valence of tooeleite is +3. These characteristic bands in the IR and Raman spectra provide useful basis for identifying the mineral tooeleite.

  14. Partners in International Research and Education: Student Contributions to the Collaborative Investigation of Bezymianny, Shiveluch, and Karymsky Volcanoes, Kamchatka, Russia and Mount St. Helens, WA, USA.

    NASA Astrophysics Data System (ADS)

    Shipman, J. S.; Kayzar, T. M.; Team, P.

    2008-12-01

    Undergraduate and graduate students as well as senior researchers from the U.S., Russia, and Japan are investigating volcanism as participants of the National Science Foundation initiative Partners in International Research and Education (PIRE). The goal of this study is to use the benefits of global comparisons to increase our understanding of explosive volcanism while at the same time developing international collaboration between scientists in the U.S., Russia, and Japan. International collaboration is established through field work in Kamchatka, Russia investigating the active systems of Bezymianny, Shiveluch, and Karymsky volcanoes with a specific focus on historic collapse-blast type eruptions. The Kamchatka volcanic arc provides unique access to multiple active volcanic systems that can be compared and contrasted to the well-studied behavior at Mount St. Helens, WA., USA. Conversely, Mount St. Helens also provides a field setting for Russian and Japanese students to be incorporated in U.S. research. Student participants employ their respective techniques in geochemistry, geophysics, petrology, and remote sensing to study the eruption response of Bezymianny and Shiveluch volcanoes, which have experienced edifice collapse. During the 2008 field season, the increased activity at Bezymianny volcano shortened a planned field expedition. In order to preserve the integrity of the program and provide a safer environment for researchers, alternative field studies began at Karymsky volcano. In July, an anonymously large eruption at Karymsky volcano permitted the collection of unique real-time data of the eruptive event. Here we present student research from three field seasons in the Kamchatka volcanic arc and associated workshops at Mount St. Helens, WA. Results include estimates of magma storage depth, gas emissions measurements, evidence for dynamic thermal regime changes in fresh volcanic deposits, and data constraining magma inputs and sources at each volcano. By

  15. Water content in arc basaltic magma in the Northeast Japan and Izu arcs: an estimate from Ca/Na partitioning between plagioclase and melt

    NASA Astrophysics Data System (ADS)

    Ushioda, M.; Takahashi, E.; Hamada, M.; Suzuki, T.

    2015-12-01

    The variation in water content of arc basaltic magmas in the Northeast Japan arc and the Izu arc was estimatedusing a simple plagioclase phenocryst hygrometer. In order to construct a plagioclase phenocryst hygrometeroptimized for arc basalt magmas, we have conducted hydrous melting experiments of relatively primitive basaltfrom the Miyakejima volcano, a frontal-arc volcano in the Izu arc. As a result of the experiments, we found that theCa/Na partition coefficient between plagioclase and hydrous basaltic melt increases linearly with an increase in H2Ocontent in the melts. We then compiled published geochemical data sets of relatively primitive basaltic rocks with no evidence of magma mixing and the most frequent Ca-rich plagioclase phenocrysts from 15 basaltic arc volcanoesincluding both frontal-arc and rear-arc volcanoes. In the 15 volcanoes studied, plagioclase phenocrysts of high anorthitecontent (An > 90) were commonly observed, whereas plagioclase phenocrysts in rear arc volcanoes usually had a loweranorthite content (90 > An > 80). In all volcanoes studied, the estimated H2O content of basaltic magma was at least3 wt.% H2O or higher. The magmas of volcanoes located on the volcanic front have about 5 wt.% H2O in magmawhereas those from the rear-arc side are slightly lower in H2O content.

  16. Predicting the Timing and Location of the next Hawaiian Volcano

    ERIC Educational Resources Information Center

    Russo, Joseph; Mattox, Stephen; Kildau, Nicole

    2010-01-01

    The wealth of geologic data on Hawaiian volcanoes makes them ideal for study by middle school students. In this paper the authors use existing data on the age and location of Hawaiian volcanoes to predict the location of the next Hawaiian volcano and when it will begin to grow on the floor of the Pacific Ocean. An inquiry-based lesson is also…

  17. How Do Volcanoes Affect Human Life? Integrated Unit.

    ERIC Educational Resources Information Center

    Dayton, Rebecca; Edwards, Carrie; Sisler, Michelle

    This packet contains a unit on teaching about volcanoes. The following question is addressed: How do volcanoes affect human life? The unit covers approximately three weeks of instruction and strives to present volcanoes in an holistic form. The five subject areas of art, language arts, mathematics, science, and social studies are integrated into…

  18. Living with Volcanoes: Year Eleven Teaching Resource Unit.

    ERIC Educational Resources Information Center

    Le Heron, Kiri; Andrews, Jill; Hooks, Stacey; Larnder, Michele; Le Heron, Richard

    2000-01-01

    Presents a unit on volcanoes and experiences with volcanoes that helps students develop geography skills. Focuses on four volcanoes: (1) Rangitoto Island; (2) Lake Pupuke; (3) Mount Smart; and (4) One Tree Hill. Includes an answer sheet and resources to use with the unit. (CMK)

  19. Full-wave Ambient Noise Tomography of Mt Rainier volcano, USA

    NASA Astrophysics Data System (ADS)

    Flinders, Ashton; Shen, Yang

    2015-04-01

    Mount Rainier towers over the landscape of western Washington (USA), ranking with Fuji-yama in Japan, Mt Pinatubo in the Philippines, and Mt Vesuvius in Italy, as one of the great stratovolcanoes of the world. Notwithstanding its picturesque stature, Mt Rainier is potentially the most devastating stratovolcano in North America, with more than 3.5 million people living beneath is shadow in the Seattle-Tacoma area. The primary hazard posed by the volcano is in the form of highly destructive debris flows (lahars). These lahars form when water and/or melted ice erode away and entrain preexisting volcanic sediment. At Mt Rainier these flows are often initiated by sector collapse of the volcano's hydrothermally rotten flanks and compounded by Mt Rainier's extensive snow and glacial ice coverage. It is therefore imperative to ascertain the extent of the volcano's summit hydrothermal alteration, and determine areas prone to collapse. Despite being one of the sixteen volcanoes globally designated by the International Association of Volcanology and Chemistry of the Earth's Interior as warranting detailed and focused study, Mt Rainier remains enigmatic both in terms of the shallow internal structure and the degree of summit hydrothermal alteration. We image this shallow internal structure and areas of possible summit alteration using ambient noise tomography. Our full waveform forward modeling includes high-resolution topography allowing us to accuratly account for the effects of topography on the propagation of short-period Rayleigh waves. Empirical Green's functions were extracted from 80 stations within 200 km of Mt Rainier, and compared with synthetic greens functions over multiple frequency bands from 2-28 seconds.

  20. Flux Pinning Properties and Magnetic Relaxation of Superconducting SmFe0.9Co0.1AsO

    NASA Astrophysics Data System (ADS)

    Zhuang, J. C.; Sun, Y.; Ding, Y.; Yuan, F. F.; Liu, J. T.; Shi, Z. X.; Li, X. W.

    2012-12-01

    Magnetic Co ion doped SmFeAsO polycrystal was synthesized via solid-state reaction. Resistivity, SEM and magnetic hysteresis loops (MHLs) were measured to investigate magnetic properties of the sample. Critical current densities as well as the flux pinning forces densities were estimated from MHLs. This paper reports for the first time the research of superconducting MHLs as well as magnetic relaxation properties of SmFe0.9Co0.1AsO. Results suggest that: (i) A tail effect in the resistivity measurement together with the rapid decrease in critical current densities at low fields shows the evidence for granularity of the sample; (ii) The asymmetry of the MHLs may be caused by the Bean-Livingstone (BL) surface pinning or granular nature, and none of theoretical models are suitable to the scaling behaviors of flux pinning forces densities; (iii) The anomalous tendency of the temperature dependence of magnetic relaxation rate as well as the effective pinning energy were observed, which may be attributed to the competition between the bulk pinning and the BL surface pinning.

  1. Scientific ballooning in Japan

    NASA Astrophysics Data System (ADS)

    Makino, Fumiyoshi

    Activities in scientific ballooning in Japan during 1998-1999 are reported. The total number of scientific balloons flown in Japan in 1998 and 1999 was sixteen, eight flights in each year. The scientific objectives were observations of high energy cosmic electrons, air samplings at various altitudes, monitoring of atmospheric ozone density, Galactic infrared observations, and test flights of new type balloons. Balloon expeditions were conducted in Antarctica by the National Institute of Polar Research, in Russia, in Canada and in India in collaboration with foreign countries' institutes to investigate cosmic rays, Galactic infrared radiation, and Earth's atmosphere. There were three flights in Antarctica, four flights in Russia, three flights in Canada and two flights in India. Four test balloons were flown for balloon technology, which included pumpkin-type super-pressure balloon and a balloon made with ultra-thin polyethylene film of 3.4 μm thickness.

  2. [Gambling disorder in Japan].

    PubMed

    Tanabe, Hitoshi

    2015-09-01

    Gambling disorder is a psychiatric disorder characterized by persistent and recurrent problematic gambling behavior, associated with impaired functioning, reduced quality of life, and frequent divorce and bankruptcy. Gambling disorder is reclassified in the category Substance-Related and Addictive Disorders in the DSM-5 because its clinical features closely resemble those of substance use disorders, and gambling activates the reward system in brain in much the same way drugs do. Prevalence of gambling disorder in Japan is high rate because of slot machines and pachinko game are very popular in Japan. The author recommend group psychotherapy and self-help group (Gamblers Anonymous), because group dynamics make them accept their wrongdoings related to gambling and believe that they can enjoy their lives without gambling. PMID:26394523

  3. Volcanoes muon imaging using Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Catalano, O.; Del Santo, M.; Mineo, T.; Cusumano, G.; Maccarone, M. C.; Pareschi, G.

    2016-01-01

    A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting of the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energy. Our new approach offers the advantage of a negligible background and an improved spatial resolution. To test the feasibility of our new method, we have carried out simulations with a toy-model based on the geometrical parameters of ASTRI SST-2M, i.e. the imaging atmospheric Cherenkov telescope currently under installation onto the Etna volcano. Comparing the results of our simulations with previous experiments based on particle detectors, we gain at least a factor of 10 in sensitivity. The result of this study shows that we resolve an empty cylinder with a radius of about 100 m located inside a volcano in less than 4 days, which implies a limit on the magma velocity of 5 m/h.

  4. Volcano hazards program in the United States

    USGS Publications Warehouse

    Tilling, R.I.; Bailey, R.A.

    1985-01-01

    Volcano monitoring and volcanic-hazards studies have received greatly increased attention in the United States in the past few years. Before 1980, the Volcanic Hazards Program was primarily focused on the active volcanoes of Kilauea and Mauna Loa, Hawaii, which have been monitored continuously since 1912 by the Hawaiian Volcano Observatory. After the reawakening and catastrophic eruption of Mount St. Helens in 1980, the program was substantially expanded as the government and general public became aware of the potential for eruptions and associated hazards within the conterminous United States. Integrated components of the expanded program include: volcanic-hazards assessment; volcano monitoring; fundamental research; and, in concert with federal, state, and local authorities, emergency-response planning. In 1980 the David A. Johnston Cascades Volcano Observatory was established in Vancouver, Washington, to systematically monitor the continuing activity of Mount St. Helens, and to acquire baseline data for monitoring the other, presently quiescent, but potentially dangerous Cascade volcanoes in the Pacific Northwest. Since June 1980, all of the eruptions of Mount St. Helens have been predicted successfully on the basis of seismic and geodetic monitoring. The largest volcanic eruptions, but the least probable statistically, that pose a threat to western conterminous United States are those from the large Pleistocene-Holocene volcanic systems, such as Long Valley caldera (California) and Yellowstone caldera (Wyoming), which are underlain by large magma chambers still potentially capable of producing catastrophic caldera-forming eruptions. In order to become better prepared for possible future hazards associated with such historically unpecedented events, detailed studies of these, and similar, large volcanic systems should be intensified to gain better insight into caldera-forming processes and to recognize, if possible, the precursors of caldera-forming eruptions

  5. Augustine Volcano, Cook Inlet, Alaska (January 12, 2006)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Since last spring, the U.S. Geological Survey's Alaska Volcano Observatory (AVO) has detected increasing volcanic unrest at Augustine Volcano in Cook Inlet, Alaska near Anchorage. Based on all available monitoring data, AVO regards that an eruption similar to 1976 and 1986 is the most probable outcome. During January, activity has been episodic, and characterized by emission of steam and ash plumes, rising to altitudes in excess of 9,000 m (30,000 ft), and posing hazards to aircraft in the vicinity. An ASTER image was acquired at 12:42 AST on January 12, 2006, during an eruptive phase of Augustine. The perspective rendition shows the eruption plume derived from the ASTER image data. ASTER's stereo viewing capability was used to calculate the 3-dimensional topography of the eruption cloud as it was blown to the south by prevailing winds. From a maximum height of 3060 m (9950 ft), the plume cooled and its top descended to 1900 m (6175 ft). The perspective view shows the ASTER data draped over the plume top topography, combined with a base image acquired in 2000 by the Landsat satellite, that is itself draped over ground elevation data from the Shuttle Radar Topography Mission. The topographic relief has been increased 1.5 times for this illustration. Comparison of the ASTER plume topography data with ash dispersal models and weather radar data will allow the National Weather Service to validate and improve such models. These models are used to forecast volcanic ash plume trajectories and provide hazard alerts and warnings to aircraft in the Alaska region.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous

  6. Sapporo, Hokkaido, Japan

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The city of Sapporo on the northernmost of the Japanese Home Island of Hokkaido (43.5N, 141.5E), host to the 1986 Winter Olympic Games is situated along the margin of a large valley which extends across the island from the Sea of Japan to the Pacific Ocean. The Valley is largely cultivated (the lighter green of the cultivated land distinguishes it from the gray urban development of Sapporo), but much of the island remains heavily forested.

  7. Mantle fault zone beneath Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Wolfe, C.J.; Okubo, P.G.; Shearer, P.M.

    2003-01-01

    Relocations and focal mechanism analyses of deep earthquakes (???13 kilometers) at Kilauea volcano demonstrate that seismicity is focused on an active fault zone at 30-kilometer depth, with seaward slip on a low-angle plane, and other smaller, distinct fault zones. The earthquakes we have analyzed predominantly reflect tectonic faulting in the brittle lithosphere rather than magma movement associated with volcanic activity. The tectonic earthquakes may be induced on preexisting faults by stresses of magmatic origin, although background stresses from volcano loading and lithospheric flexure may also contribute.

  8. Hot spot and trench volcano separations

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Schubert, G.

    1974-01-01

    It is suggested that the distribution of separations between trench volcanos located along subduction zones reflects the depth of partial melting, and that the separation distribution for hot spot volcanoes near spreading centers provides a measure of the depth of mantle convection cells. It is further proposed that the lateral dimensions of mantle convection cells are also represented by the hot-spot separations (rather than by ridge-trench distances) and that a break in the distribution of hot spot separations at 3000 km is evidence for both whole mantle convection and a deep thermal plume origin of hot spots.

  9. In search of ancestral Kilauea volcano

    USGS Publications Warehouse

    Lipman, P.W.; Sisson, T.W.; Ui, T.; Naka, J.

    2000-01-01

    Submersible observations and samples show that the lower south flank of Hawaii, offshore from Kilauea volcano and the active Hilina slump system, consists entirely of compositionally diverse volcaniclastic rocks; pillow lavas are confined to shallow slopes. Submarine-erupted basalt clasts have strongly variable alkalic and transitional basalt compositions (to 41% SiO2, 10.8% alkalies), contrasting with present-day Kilauea tholeiites. The volcaniclastic rocks provide a unique record of ancestral alkalic growth of an archetypal hotspot volcano, including transition to its tholeiitic shield stage, and associated slope-failure events.

  10. Venus small volcano classification and description

    NASA Technical Reports Server (NTRS)

    Aubele, J. C.

    1993-01-01

    The high resolution and global coverage of the Magellan radar image data set allows detailed study of the smallest volcanoes on the planet. A modified classification scheme for volcanoes less than 20 km in diameter is shown and described. It is based on observations of all members of the 556 significant clusters or fields of small volcanoes located and described by this author during data collection for the Magellan Volcanic and Magmatic Feature Catalog. This global study of approximately 10 exp 4 volcanoes provides new information for refining small volcano classification based on individual characteristics. Total number of these volcanoes was estimated to be 10 exp 5 to 10 exp 6 planetwide based on pre-Magellan analysis of Venera 15/16, and during preparation of the global catalog, small volcanoes were identified individually or in clusters in every C1-MIDR mosaic of the Magellan data set. Basal diameter (based on 1000 measured edifices) generally ranges from 2 to 12 km with a mode of 34 km, and follows an exponential distribution similar to the size frequency distribution of seamounts as measured from GLORIA sonar images. This is a typical distribution for most size-limited natural phenomena unlike impact craters which follow a power law distribution and continue to infinitely increase in number with decreasing size. Using an exponential distribution calculated from measured small volcanoes selected globally at random, we can calculate total number possible given a minimum size. The paucity of edifice diameters less than 2 km may be due to inability to identify very small volcanic edifices in this data set; however, summit pits are recognizable at smaller diameters, and 2 km may represent a significant minimum diameter related to style of volcanic eruption. Guest, et al, discussed four general types of small volcanic edifices on Venus: (1) small lava shields; (2) small volcanic cones; (3) small volcanic domes; and (4) scalloped margin domes ('ticks'). Steep

  11. Venus small volcano classification and description

    NASA Astrophysics Data System (ADS)

    Aubele, J. C.

    1993-03-01

    The high resolution and global coverage of the Magellan radar image data set allows detailed study of the smallest volcanoes on the planet. A modified classification scheme for volcanoes less than 20 km in diameter is shown and described. It is based on observations of all members of the 556 significant clusters or fields of small volcanoes located and described by this author during data collection for the Magellan Volcanic and Magmatic Feature Catalog. This global study of approximately 10 exp 4 volcanoes provides new information for refining small volcano classification based on individual characteristics. Total number of these volcanoes was estimated to be 10 exp 5 to 10 exp 6 planetwide based on pre-Magellan analysis of Venera 15/16, and during preparation of the global catalog, small volcanoes were identified individually or in clusters in every C1-MIDR mosaic of the Magellan data set. Basal diameter (based on 1000 measured edifices) generally ranges from 2 to 12 km with a mode of 34 km, and follows an exponential distribution similar to the size frequency distribution of seamounts as measured from GLORIA sonar images. This is a typical distribution for most size-limited natural phenomena unlike impact craters which follow a power law distribution and continue to infinitely increase in number with decreasing size. Using an exponential distribution calculated from measured small volcanoes selected globally at random, we can calculate total number possible given a minimum size. The paucity of edifice diameters less than 2 km may be due to inability to identify very small volcanic edifices in this data set; however, summit pits are recognizable at smaller diameters, and 2 km may represent a significant minimum diameter related to style of volcanic eruption. Guest, et al, discussed four general types of small volcanic edifices on Venus: (1) small lava shields; (2) small volcanic cones; (3) small volcanic domes; and (4) scalloped margin domes ('ticks'). Steep

  12. The origin of the Hawaiian Volcano Observatory

    SciTech Connect

    Dvorak, John

    2011-05-15

    I first stepped through the doorway of the Hawaiian Volcano Observatory in 1976, and I was impressed by what I saw: A dozen people working out of a stone-and-metal building perched at the edge of a high cliff with a spectacular view of a vast volcanic plain. Their primary purpose was to monitor the island's two active volcanoes, Kilauea and Mauna Loa. I joined them, working for six weeks as a volunteer and then, years later, as a staff scientist. That gave me several chances to ask how the observatory had started.

  13. In Brief: Russian volcano warnings reinstated

    NASA Astrophysics Data System (ADS)

    Zielinski, Sarah

    2007-04-01

    The Kamchatka Volcanic Eruption Response Team (KVERT) is again issuing warnings for aviation during periods of activity by Kamchatkan volcanoes. KVERT had stopped issuing warnings on 1 March due to a loss of funding by the Federal Unitary Enterprise State Air Traffic Management Corporation of Russia (see Eos 88(12), 2007). The funding for this work has now resumed. KVERT is a collaborative project of scientists from the Russian Institute of Volcanology and Seismology, the Kamchatka Experimental and Methodical Seismological Department, and the Alaska Volcano Observatory.

  14. Seismic Structure Beneath Taal Volcano, Philippines

    NASA Astrophysics Data System (ADS)

    You, S. H.; Gung, Y.; Konstantinou, K. I.; Lin, C. H.

    2014-12-01

    The very active Taal Volcano is situated 60 km south of Metro Manila in the southern part of Luzon Island. Based on its frequent explosive eruptions and high potential hazards to nearby population of several million, Taal Volcano is chosen as one of the 15 most dangerous "Decade Volcanoes" in the world. We deployed a temporary seismic network consisting of 8 stations since March 2008. The temporal network was operated from late March 2008 to mid March 2010 and recorded over 2270 local earthquakes. In the early data processing stages, unexpected linear drifting of clock time was clearly identified from ambient noise cross-correlation functions for a number of stations. The drifting rates of all problematic stations were determined as references to correct timing errors prior to further processing. Initial locations of earthquakes were determined from manually picking P- and S-phases arrivals with a general velocity model based on AK135. We used travel times of 305 well-located local events to derive a minimum 1-D model using VELEST. Two major earthquake groups were noticed from refined locations. One was underneath the western shore of Taal Lake with a linear feature, and the other spread at shallower depths showing a less compact feature around the eastern flank of Taal Volcano Island. We performed seismic tomography to image the 3D structure beneath Taal Volcano using a well-established algorithm, LOTOS. Some interesting features are noted in the tomographic results, such as a probable solidified past magma conduit below the northwestern corner of Taal Volcano Island, characterized by high Vp, Vs, and low Vp/Vs ratio, and a potential large hydrothermal reservoir beneath the central of Taal Volcano Island, characterized by low Vs and high Vp/Vs ratio. Combining the results of seismicity and tomographic images, we also suggest the potential existence of a magma chamber beneath the southwestern Taal Lake, and a magma conduit or fault extending from there to the

  15. Psychology in Japan.

    PubMed

    Imada, Hiroshi; Tanaka-Matsumi, Junko

    2016-06-01

    The purpose of this article is to provide information about Japan and its psychology in advance of the 31st International Congress of Psychology (ICP), to be held in Yokohama, Japan, in 2016. The article begins with the introduction of the Japanese Psychological Association (JPA), the hosting organization of the ICP 2016, and the Japanese Union of Psychological Associations consisting of 51 associations/societies, of which the JPA is a member. This is followed by a brief description of a history of psychology of Japan, with emphasis on the variation in our approach to psychology in three different periods, that is, the pre- and post-Pacific War periods, and the post-1960 period. Next, the international contributions of Japanese psychology/psychologists are discussed from the point of view of their visibility. Education and training in psychology in Japanese universities is discussed with a final positive remark about the long-awaited enactment of the Accredited Psychologist Law in September, 2015. PMID:26892102

  16. Seismicity of the Earth 1900-2007, Japan and Vicinity

    USGS Publications Warehouse

    Rhea, Susan; Tarr, Arthur C.; Hayes, Gavin P.; Villaseñor, Antonio; Benz, Harley

    2010-01-01

    This map shows details of Japan and vicinity not visible in an earlier publication, U.S. Geological Survey Scientific Investigations Map 3064. Japan and its island possessions lie across four major tectonic plates: Pacific plate, North America plate; Eurasia plate; and Philippine Sea plate. The Pacific plate is subducted into the mantle, beneath Hokkaido and northern Honshu, along the eastern margin of the Okhotsk microplate, a proposed subdivision of the North America plate (Bird, 2003). Farther south, the pacific plate is subducted beneath volcanic islands along the eastern margin of the Philippine Sea plate. This 2,200 km-long zone of subduction of the Pacific plate is responsible for the creation of the deep offshore Ogasawara and Japan trenches as well as parallel chains of islands and volcanoes, typical of the Circumpacific island arcs. Similarly, the Philippine Sea plate is itself subducting under the Eurasia plate along a zone, extending from Taiwan to southern Honshu, that comprises the Ryuku Islands and the Nansei-Shonto trench.

  17. Volcano shapes, entropies, and eruption probabilities

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust; Mohajeri, Nahid

    2014-05-01

    We propose that the shapes of polygenetic volcanic edifices reflect the shapes of the associated probability distributions of eruptions. In this view, the peak of a given volcanic edifice coincides roughly with the peak of the probability (or frequency) distribution of its eruptions. The broadness and slopes of the edifices vary widely, however. The shapes of volcanic edifices can be approximated by various distributions, either discrete (binning or histogram approximation) or continuous. For a volcano shape (profile) approximated by a normal curve, for example, the broadness would be reflected in its standard deviation (spread). Entropy (S) of a discrete probability distribution is a measure of the absolute uncertainty as to the next outcome/message: in this case, the uncertainty as to time and place of the next eruption. A uniform discrete distribution (all bins of equal height), representing a flat volcanic field or zone, has the largest entropy or uncertainty. For continuous distributions, we use differential entropy, which is a measure of relative uncertainty, or uncertainty change, rather than absolute uncertainty. Volcano shapes can be approximated by various distributions, from which the entropies and thus the uncertainties as regards future eruptions can be calculated. We use the Gibbs-Shannon formula for the discrete entropies and the analogues general formula for the differential entropies and compare their usefulness for assessing the probabilities of eruptions in volcanoes. We relate the entropies to the work done by the volcano during an eruption using the Helmholtz free energy. Many factors other than the frequency of eruptions determine the shape of a volcano. These include erosion, landslides, and the properties of the erupted materials (including their angle of repose). The exact functional relation between the volcano shape and the eruption probability distribution must be explored for individual volcanoes but, once established, can be used to

  18. Interpretation of the Hydrothermal System in Kirishima Hot Spring Village, Southern Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Yonekura, Yusaku; Fujimitsu, Yasuhiro; Nishijima, Jun

    2014-05-01

    It is very important to understand hydrothermal systems for sustainable utilizing of hot springs. However, in Japan, most of the large hot springs are located in national parks. Therefore, explorations such as geochemical, geophysical or boring surveys to interpret the hydrothermal systems had not been conducted enough. For this reason, hydrothermal systems of some hot springs in Japan have not been made clear even now. We constructed a conceptual model to interpret the hydrothermal system of Kirishima Hot Spring Village in Kirishima national park, southern part of Kyushu, Japan. There are many hot springs in Kirishima Hot Spring Village, such as Maruo, Hayashida, and Myoban hot spring areas. Kirishima Hot Spring Village is located in southwestern part of Kirishima volcanoes, like Onami-ike volcano, and the altitude of Maruo area is about 600 m and that of Hayashida and Myoban areas is about 800 m. In order to interpret the hydrothermal system in Kirishima Hot Spring Village, we need to understand three important factors which are heat source, hot spring water, and subsurface structure. In January 2011, Shinmoe-dake volcano of Kirishima volcanoes made a large scale eruption. Then, the pressure source of Kirishima volcanoes is expected to be located in about 2 km west of Onami-ike volcano and its estimated altitude is about -7 km (Kobayashi et al., 2011). We used this pressure source for our conceptual model as a heat source. Secondary, we tried to clarify the fluid of Kirishima Hot Spring Village by considering the chemical compositions of hot spring water. In addition, we made a Na-K-Mg diagram to estimate the reservoir temperature and find that spring water has reached equilibrium or not. As a result, we supposed that hot spring water of Maruo area is magmatic, and that of Hayashida and Myoban area is consisted of sulfate and meteoric water. Thirdly, we used gravity data, which is the result from previous study and our field survey, to make a residual Bouguer

  19. Volcanic subsidence triggered by the 2011 Tohoku earthquake in Japan: Hot and weak material hypothesis

    NASA Astrophysics Data System (ADS)

    Takada, Youichiro; Fukushima, Yo

    2014-05-01

    With spaceborne interferometric synthetic aperture radar (InSAR) analysis, we found that the 2011 Mw 9.0 Tohoku earthquake in Japan (March 11, 2011) has triggered unprecedented subsidence of multiple volcanoes. Similar phenomenon has been reported for the 2010 Mw 8.8 Maule earthquake (Pritchard et al., 2013). We used SAR data acquired before and after the mainshock by ALOS (PALSAR). By removing long wave-length phase trend from InSAR images, we obtained the localized subsidence signals at five active volcanoes: Mt. Akitakoma, Mt. Kurikoma, Mt. Zao, Mt. Azuma, and Mt. Nasu. All of them belong to the volcanic front of Northeast Japan. The subsidence areas exhibit elliptic shape elongated in the North-South direction - perpendicular to the principal axis of the extensional stress change due to the Tohoku earthquake. Major axis of the ellipse reaches 15 - 20 km, and the amount of subsidence is up to 15 cm (Mt. Azuma). GPS data from two volcanoes also indicate surface subsidence consistent with the satellite radar observations. Furthermore, the GPS data show that the subsidence occurred immediately after the earthquake. A common feature of the five volcanoes is their high geothermal activity. The areas of high geothermal gradient and high thermal water temperature are in good agreement with the area of subsidence detected by InSAR. Also, the Late Cenozoic calderas cluster around the subsidence regions, which implies that hot plutonic bodies once intruded are still hot and highly deformable even now. According to numerical modelling, the observed subsidence can be explained by the co-seismic response of fluid-filled ellipsoid beneath each volcano. We confirmed that the surface subsidence is also caused by the ellipsoid filled with elastic body of low shear strength. We further checked that an ellipsoid is more effective to cause the subsidence than a sphere when the ellipsoid is elongated perpendicular to the tension axis of the imposed stress. References: Takada, Y. and

  20. Mobile Response Team Saves Lives in Volcano Crises

    USGS Publications Warehouse

    Ewert, John W.; Miller, C. Dan; Hendley, James W., II; Stauffer, Peter H.

    1997-01-01

    The world's only volcano crisis response team, organized and operated by the USGS, can be quickly mobilized to assess and monitor hazards at volcanoes threatening to erupt. Since 1986, the team has responded to more than a dozen volcano crises as part of the Volcano Disaster Assistance Program (VDAP), a cooperative effort with the Office of Foreign Disaster Assistance of the U.S. Agency for International Development. The work of USGS scientists with VDAP has helped save countless lives, and the valuable lessons learned are being used to reduce risks from volcano hazards in the United States.

  1. Digital data set of volcano hazards for active Cascade Volcanos, Washington

    USGS Publications Warehouse

    Schilling, Steve P.

    1996-01-01

    Scientists at the Cascade Volcano Observatory have completed hazard assessments for the five active volcanos in Washington. The five studies included Mount Adams (Scott and others, 1995), Mount Baker (Gardner and others, 1995), Glacier Peak (Waitt and others, 1995), Mount Rainier (Hoblitt and others, 1995) and Mount St. Helens (Wolfe and Pierson, 1995). Twenty Geographic Information System (GIS) data sets have been created that represent the hazard information from the assessments. The twenty data sets have individual Open File part numbers and titles

  2. Detecting Volcano-Tectonic Earthquakes at the Tatun Volcano Group in Taiwan with Dense Arrays

    NASA Astrophysics Data System (ADS)

    Sun, W. F.; Lin, C. H.; Chang, W. Y.

    2015-12-01

    The Tatun Volcano Group (TVG) is located at the northernmost tip of the island of Taiwan. Although TVG have been erupted 0.1-0.2 Ma ago and are considered being extinct, some recent studies suggest that they are active or dormant volcanos. We perform a systematic detection of volcano-tectonic earthquakes beneath TVG using three dense, small-aperture seismic arrays, which were deployed for six months in 2012. We use broadband frequency-wavenumber beam forming and moving-window grid-search methods to compute array parameters for all nearly continuous data and identify volcano-tectonic earthquakes. We detect much more events than that listed in the TVG volcano-tectonic earthquake catalog, about 50 events per month. Our results suggest that dense array techniques are capable of capturing detailed spatiotemporal evolution of volcano-tectonic earthquake behaviours at TVG, and also help to better understand the source mechanism of the brittle, uppermost part of the crust to the combined effect of the local hydrothermal fluid pressure and the regional stress field in the volcanic environment.

  3. Multidisciplinary Monitoring Experiments at Kawah Ijen Volcano

    NASA Astrophysics Data System (ADS)

    Gunawan, Hendra; Pallister, John; Caudron, Corentin

    2014-12-01

    "Wet volcanoes" with crater lakes and extensive hydrothermal systems pose challenges for monitoring and forecasting eruptions. That's because their lakes and hydrothermal systems serve as reservoirs for magmatic heat and fluid emissions, filtering and delaying the surface expressions of magmatic unrest.

  4. Biological Studies on a Live Volcano.

    ERIC Educational Resources Information Center

    Zipko, Stephen J.

    1992-01-01

    Describes scientific research on an Earthwatch expedition to study Arenal, one of the world's most active volcanoes, in north central Costa Rica. The purpose of the two-week project was to monitor and understand the past and ongoing development of a small, geologically young, highly active stratovolcano in a tropical, high-rainfall environment.…

  5. Preliminary radon measurements at Villarrica volcano, Chile

    NASA Astrophysics Data System (ADS)

    Cigolini, C.; Laiolo, M.; Coppola, D.; Ulivieri, G.

    2013-10-01

    We report data from a radon survey conducted at Villarrica volcano. Measurements have been obtained at selected sites by E-PERM® electrets and two automatic stations utilizing DOSEman detectors (SARAD Gmbh). Mean values for Villarrica are 1600 (±1150) Bq/m3 are similar to values recorded at Cerro Negro and Arenal in Central America. Moderately higher emissions, at measurement sites, were recorded on the NNW sector of the volcano and the summit, ranging from 1800 to 2400 Bq/m3. These measurements indicate that this area could potentially be a zone of flank weakness. In addition, the highest radon activities, up to 4600 Bq/m3, were measured at a station located near the intersection of the Liquiñe-Ofqui Fault Zone with the Gastre Fault Zone. To date, the Villarrica radon measurements reported here are, together with those collected at Galeras (Colombia), the sole radon data reported from South American volcanoes. This research may contribute to improving future geochemical monitoring and volcano surveillance.

  6. Different types of small volcanos on Venus

    NASA Technical Reports Server (NTRS)

    Slyuta, E. N.; Shalimov, I. V.; Nikishin, A. M.

    1992-01-01

    One of the studies of volcanic activity on Venus is the comparison of that with the analogous volcanic activity on Earth. The preliminary report of such a comparison and description of a small cluster of small venusian volcanos is represented in detail in this paper.

  7. Bathymetry of southern Mauna Loa Volcano, Hawaii

    USGS Publications Warehouse

    Chadwick, William W.; Moore, James G.; Garcia, Michael O.; Fox, Christopher G.

    1993-01-01

    Manua Loa, the largest volcano on Earth, lies largely beneath the sea, and until recently only generalized bathymetry of this giant volcano was available. However, within the last two decades, the development of multibeam sonar and the improvement of satellite systems (Global Positioning System) have increased the availability of precise bathymetric mapping. This map combines topography of the subaerial southern part of the volcano with modern multibeam bathymetric data from the south submarine flank. The map includes the summit caldera of Mauna Loa Volcano and the entire length of the 100-km-long southwest rift zone that is marked by a much more pronounced ridge below sea level than above. The 60-km-long segment of the rift zone abruptly changes trend from southwest to south 30 km from the summit. It extends from this bend out to sea at the south cape of the island (Kalae) to 4 to 4.5 km depth where it impinges on the elongate west ridge of Apuupuu Seamount. The west submarine flank of the rift-zone ridge connects with the Kahuku fault on land and both are part of the ampitheater head of a major submarine landslide (Lipman and others, 1990; Moore and Clague, 1992). Two pre-Hawaiian volcanic seamounts in the map area, Apuupuu and Dana Seamounts, are apparently Cretaceous in age and are somewhat younger than the Cretaceous oceanic crust on which they are built.

  8. Seismicity at Baru Volcano, Western Panama, Panama

    NASA Astrophysics Data System (ADS)

    Camacho, E.; Novelo-Casanova, D. A.; Tapia, A.; Rodriguez, A.

    2008-12-01

    The Baru volcano in Western Panama (8.808°N, 82.543°W) is a 3,475 m high strato volcano that lies at about 50 km from the Costa Rican border. The last major eruptive event at this volcano occurred c.1550 AD and no further eruptive activity from that time is known. Since the 1930´s, approximately every 30 years a series of seismic swarms take place in the surroundings of the volcanic edifice. Theses swarms last several weeks alarming the population who lives near the volcano. The last of these episodes occurred on May 2006 and lasted one and a half months. More than 20,000 people live adjacent to the volcano and any future eruption has the potential to be very dangerous. In June 2007, a digital seismic monitoring network of ten stations, linked via internet, was installed around the volcano in a collaborative project between the University of Panama and the Panamanian Government. The seismic data acquisition at the sites is performed using LINUX-SEISLOG and the events are recorded by four servers at different locations using the Earth Worm system. In this work we analyze the characteristics of the volcano seismicity recorded from May 4th, 2006 to July 31st, 2008 by at least 4 stations and located at about 15 km from the summit. To determine the seismic parameters, we tested several crustal velocity models and used the seismic analysis software package SEISAN. Our final velocity model was determined using seismic data for the first four km obtained from a temporal seismic network deployed in 1981 by the British Geological Survey (BGS) as part of geothermal studies conducted at Cerro Pando, Western Panama Highlands. Our results indicate that all the events recorded in the quadrant 8.6-9.0°N and 82.2-82.7°W are located in the depth range of 0.1 to 8 km. Cross sections show vertical alignments of hypocenters below the summit although most of the seismicity is concentrated in its eastern flank reaching the town of Boquete. All the calculated focal mechanisms are of

  9. Hazard maps of Colima volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nunez-Cornu, F. J.; Escudero Ayala, C. R.

    2011-12-01

    Colima volcano, also known as Volcan de Fuego (19° 30.696 N, 103° 37.026 W), is located on the border between the states of Jalisco and Colima and is the most active volcano in Mexico. Began its current eruptive process in February 1991, in February 10, 1999 the biggest explosion since 1913 occurred at the summit dome. The activity during the 2001-2005 period was the most intense, but did not exceed VEI 3. The activity resulted in the formation of domes and their destruction after explosive events. The explosions originated eruptive columns, reaching attitudes between 4,500 and 9,000 m.a.s.l., further pyroclastic flows reaching distances up to 3.5 km from the crater. During the explosive events ash emissions were generated in all directions reaching distances up to 100 km, slightly affected nearby villages as Tuxpan, Tonila, Zapotlán, Cuauhtemoc, Comala, Zapotitlan de Vadillo and Toliman. During the 2005 this volcano has had an intense effusive-explosive activity, similar to the one that took place during the period of 1890 through 1900. Intense pre-plinian eruption in January 20, 1913, generated little economic losses in the lower parts of the volcano due to low population density and low socio-economic activities at the time. Shows the updating of the volcanic hazard maps published in 2001, where we identify whit SPOT satellite imagery and Google Earth, change in the land use on the slope of volcano, the expansion of the agricultural frontier on the east and southeast sides of the Colima volcano, the population inhabiting the area is approximately 517,000 people, and growing at an annual rate of 4.77%, also the region that has shown an increased in the vulnerability for the development of economic activities, supported by the construction of highways, natural gas pipelines and electrical infrastructure that connect to the Port of Manzanillo to Guadalajara city. The update the hazard maps are: a) Exclusion areas and moderate hazard for explosive events

  10. The Anatahan volcano-monitoring system

    NASA Astrophysics Data System (ADS)

    Marso, J. N.; Lockhart, A. B.; White, R. A.; Koyanagi, S. K.; Trusdell, F. A.; Camacho, J. T.; Chong, R.

    2003-12-01

    A real-time 24/7 Anatahan volcano-monitoring and eruption detection system is now operational. There had been no real-time seismic monitoring on Anatahan during the May 10, 2003 eruption because the single telemetered seismic station on Anatahan Island had failed. On May 25, staff from the Emergency Management Office (EMO) of the Commonwealth of the Northern Mariana Islands and the U. S. Geological Survey (USGS) established a replacement telemetered seismic station on Anatahan whose data were recorded on a drum recorder at the EMO on Saipan, 130 km to the south by June 5. In late June EMO and USGS staff installed a Glowworm seismic data acquisition system (Marso et al, 2003) at EMO and hardened the Anatahan telemetry links. The Glowworm system collects the telemetered seismic data from Anatahan and Saipan, places graphical display products on a webpage, and exports the seismic waveform data in real time to Glowworm systems at Hawaii Volcano Observatory and Cascades Volcano Observatory (CVO). In early July, a back-up telemetered seismic station was placed on Sarigan Island 40 km north of Anatahan, transmitting directly to the EMO on Saipan. Because there is currently no population on the island, at this time the principal hazard presented by Anatahan volcano