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Lautze, N. C.
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Lautze, N. C.
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- PublicationRestrictedInsights into explosion dynamics and the production of ash at Stromboli from samples collected in real-time, October 2009(2013-12-29)
; ; ; ; ; ; ;Lautze, N.; Hawaii Institute of Geophysics and Planetology, University of Hawaii–Manoa, 1680 East West Road, Honolulu, Hawaii 96825, USA, and Department of Seismology and Tectonophysics, Istituto Nazionale di Geofi sica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome, Italy ;Taddeucci, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Andronico, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Houghton, B.; Department of Geology and Geophysics, University of Hawaii–Manoa, 1680 East West Road, Honolulu, Hawaii 96825, USA ;Niemeijer, A.; Utrecht University, Faculty of Geosciences–High Pressure and Temperature Laboratory, Budapestlaan 4, 3584 CD, Utrecht, the Netherlands ;Scarlato, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; Rapid characterization of tephra from ongoing explosive eruptions can provide valuable insights into eruptive mechanisms, especially when integrated with data from other monitoring systems. Here we gain perspective on Stromboli’s eruptive processes by linking the characteristics of ash collected in real-time with videos of each explosion. A 3 day, multifaceted fi eld campaign at Stromboli was undertaken by Italy’s Istituto Nazionale di Geofi sica e Vulcanologia in October 2009. At this time, activity was at a moderately intense level, with the occurrence of an average of 4– 5 explosions per hour at each of the SW and NE craters. Eight ash samples were analyzed using binocular and scanning electron microscopes to gain data on the components, grain size and morphology distributions, and surface chemistry of ash particles within each sample. Monitoring video of each explosion enabled an estimation of the duration and height of each sampled explosion. In each sample, the proportion of fl uidal, glassy sideromelane (as opposed to blocky, microcrystalline tachylite plus lithics), the degree of “chemical freshness” (as opposed to alteration), and the average size of particles appear to correlate with the explosion “type” described in previous studies, and the maximum launch height of the corresponding explosion. Our observations suggest that more violent explosions (i.e., those driven by the liberation of larger and/or more pressurized gas volumes) can be associated with type 2a conditions and the fragmentation of hot and low- viscosity magma, while weaker type 2b explosions erupt predominantly ash-sized particles derived from the fragmentation of colder, more outgassed magma and passive integration of lithic wall debris. The formation of fl uidal sideromelane ash particles (up to Pele’s hair) requires the aerodynamic deformation of a relatively low-viscosity magma and demonstrates unequivocally that ash at Stromboli is not derived entirely from wall rock and/or brittle fragmentation of stagnant magma. We suggest that this ash-sized material forms through rapid acceleration and breakup of larger magma fragments, as supported by evidence from high-speed video of two of the sampled explosions.245 67 - PublicationRestrictedSEM-based methods for the analysis of basaltic ash from weak explosive activity at Etna in 2006 and the 2007 eruptive crisis at Stromboli(2012)
; ; ; ; ; ; ; ; ;Lautze, N. C.; University of Hawaii, Manoa, Department of Geology and Geophysics, United States ;Taddeucci, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Andronico, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cannata, C.; Univerista della Calabria, Italy ;Tornetta, L.; University of Hawaii, Manoa, Department of Geology and Geophysics, United States ;Scarlato, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Houghton, B.; University of Hawaii, Manoa, Department of Geology and Geophysics, United States ;Lo Castro, M. D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; ; ; ; We present results from a semi-automated field-emission scanning electron microscope investigation of basaltic ash from a variety of eruptive processes that occurred at Mount Etna volcano in 2006 and at Stromboli volcano in 2007. From a methodological perspective, the proposed techniques provide relatively fast (about 4 h per sample) information on the size distribution, morphology, and surface chemistry of several hundred ash particles. Particle morphology is characterized by compactness and elongation parameters, and surface chemistry data are shown using ternary plots of the relative abundance of several key elements. The obtained size distributions match well those obtained by an independent technique. The surface chemistry data efficiently characterize the chemical composition, type and abundance of crystals, and dominant alteration phases in the ash samples. From a volcanological perspective, the analyzed samples cover a wide spectrum of relatively minor ash-forming eruptive activity, including weak Hawaiian fountaining at Etna, and lava-sea water interaction, weak Strombolian explosions, vent clearing activity, and a paroxysm during the 2007 eruptive crisis at Stromboli. This study outlines subtle chemical and morphological differences in the ash deposited at different locations during the Etna event, and variable alteration patterns in the surface chemistry of the Stromboli samples specific to each eruptive activity. Overall, we show this method to be effective in quantifying the main features of volcanic ash particles from the relatively weak – and yet frequent – explosive activity occurring at basaltic volcanoes.169 25 - PublicationRestrictedPulsed lava effusion at Mount Etna during 2001(2004-09-30)
; ; ; ; ; ; ; ; ;Lautze, N. C.; Department of Geology and Geophysics, SOEST, University of Hawaii, 1680 East–West Road, Post 606A, Honolulu, HI 96822, USA ;Harris, A. J. L.; Department of Geology and Geophysics, SOEST, University of Hawaii, 1680 East–West Road, Post 606A, Honolulu, HI 96822, USA - HIGP/SOEST, University of Hawaii, Honolulu, HI 96822, USA ;Bailey, J. E.; Department of Geology and Geophysics, SOEST, University of Hawaii, 1680 East–West Road, Post 606A, Honolulu, HI 96822, USA - HIGP/SOEST, University of Hawaii, Honolulu, HI 96822, USA ;Ripepe, M.; Dipartimento di Scienze della Terra, Università di Firenze, Florence , Italy ;Calvari, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Dehn, J.; Alaska Volcano Observatory, Fairbanks, AK , USA ;Rowland, S.; HIGP/SOEST, University of Hawaii, Honolulu, HI 96822, USA ;Evans-Jones, K.; NERC Remote Sensing Data Analysis Service, Plymouth Marine Laboratory, Plymouth , UK; ; ; ; ; ;; Effusion rate and degassing data collected at Mt. Etna volcano (Italy) in 2001 show variations occurring on time scales of hours to months. We use both long- and short-term data sets spanning January to August to identify this variation. The long data sets comprise a satellite- and ground-based time series of effusion rates, and the latter include field-based effusion rate and degassing data collected May 29–31. The satellite-derived effusion rates for January through August reveal four volumetric pulses that are characterized by increasing mean effusion rate values and lead up to the 2001 flank eruption. Peak effusion rates during these 23–57 day pulses were 1.2 m3 s-1 in Pulse 1 (1 Jan–4 Mar), 1.1 m3 s-1 in Pulse 2 (5 Mar–21 Apr), 4.2 m3 s-1 in Pulse 3 (24 Apr–18 Jun), 8.8 m3 s-1 in Pulse 4 (23 Jun–16 Jul), and 22.2 m3 s-1 during the flank eruption (17 Jul–9 Aug). Rank-order analysis of the satellite data shows that effusion rate values during the 2001 flank eruption define a statistically different trend than Etna's persistent activity from Jan 1 to Jul 17. Data prior to the flank eruption obey a power-law relationship that may define an effusion rate threshold of ~3–5 m3 s-1 for Etna's typical persistent activity. Our short-term data coincide with the satellite-derived peak effusion period of Pulse 3. Degassing (at-vent puff frequency) shows a general increase from May 29 to 31, with hour-long variations in both puff frequency and lava flow velocity (effusion rate). We identify five 3–14 h degassing periods that contain 26 shorter (19–126 min-long) oscillations. This variation shows some positive correlation with effusion rate measurements during the same time period. If a relationship between puff frequency and effusion rate is valid, we propose that their short-term variation is the result of changes in the supply rate of magma to the near-vent conduit system. Therefore, these short-term data provide some evidence that the clear weeks- to months-long variation in Etna's effusive activity (January–August 2001) was overprinted by a minutes- to hour-scale oscillation in shallow supply.168 79