scholarly journals The submarine record of a large-scale explosive eruption in the Vanuatu Arc: ∼1 Ma Efaté Pumice Formation

2003 ◽  
pp. 273-283 ◽  
Author(s):  
Alison M. Raos ◽  
Jocelyn McPhie
Keyword(s):  
Large Scale ◽  
Explosive Eruption

Hidden earthquakes unveil the dynamic evolution of a large-scale explosive eruption

2020 ◽  
Author(s):  
Ricardo Garza-Giron ◽  
Emily Brodsky ◽  
Zack Spica ◽  
Matt Haney
Keyword(s):  
Large Scale ◽  
Explosive Eruption ◽  
Volcanic Eruptions ◽  
Spatiotemporal Analysis ◽  
Detection Methods ◽  
Magnitude Distribution ◽  
Volcano Observatory ◽  
Earthquake Detection ◽  
Aftershock Sequences ◽  
Hydrological System

<p>Volcanic eruptions progress by co-evolving the fluid and solid systems. The fluid mechanics can be observed through the evolution of plumes and ejecta. How does the solid evolve? When does the conduit open? When does it close? Seismology can potentially tell us about these processes by measuring the failure of the solid rock. However, such inferences require detection of earthquakes during an explosive eruption. Standard earthquake detection methods often fail during this time as the eruption itself produces seismic noise that obscures the earthquakes. In this work, we address this problem by applying both a supervised and unsupervised search techniques to the existing catalog of the 2008 Okmok Caldera eruption to find brittle failure signals during the continuous eruptive sequence. We were able to detect >4500 new earthquakes using the 419 events previously located by the Alaska Volcano Observatory (AVO). A spatiotemporal analysis of the occurrence of earthquakes during the eruption reveal interesting observations: Seismic bursts during the eruption are not synchronized with the exhalation of large ash and steam plumes, suggesting that the dynamics of the eruption are controlled by a clog-and-crack mechanism; most of the Caldera co-eruptive seismicity that is not located at the focus of the eruption occurs under the intra-Caldera cones, showing the activation of their hydrological system due to a system-wide pressurization; the end of the eruption is marked by a large burst of small, deep earthquakes trending SW-NE, possibly related to a propagating lateral dike similar to those observed in other basaltic calderas; the magnitude distribution of seismicity through time shows that the largest earthquakes in the bursts do not happen at the beginning of the sequence like in typical mainshock-aftershock sequences. Furthermore, high precision earthquake relocations highlight a ring-fault structure inside of Okmok Caldera which is thought to be acting as the pathway for fluids to the surface.</p>

scholarly journals Practising an explosive eruption in Iceland: outcomes from a European exercise

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Claire Witham ◽  
Sara Barsotti ◽  
Stéphanie Dumont ◽  
Björn Oddsson ◽  
Freysteinn Sigmundsson
Keyword(s):  
Large Scale ◽  
Explosive Eruption ◽  
Simulated Data ◽  
Volcanic Hazards ◽  
Civil Protection ◽  
Volcano Observatory ◽  
European Science ◽  
Science Community ◽  
Media Interaction ◽  
University Science

AbstractA 3 day exercise simulating unrest and a large explosive eruption at Katla volcano, Iceland, was conducted in January 2016. A large volume of simulated data based on a complex, but realistic eruption scenario was compiled in advance and then transmitted to exercise participants in near-real time over the course of the exercise. The scenario was designed to test the expertise and procedures of the local institutions in charge of warning and responding to volcanic hazards, namely the volcano observatory, national civil protection, and the local university-science sector, as well as their interactions with the European science community and the London Volcanic Ash Advisory Centre. This exercise was the first of this magnitude and scope in Iceland and has revealed many successful developments introduced since the 2010 Eyjafjallajökull and 2011 Grímsvötn eruptions. Following the exercise, 90% of participants said that they felt better prepared for a future eruption. As with any exercise, it also identified areas where further development is required and improvements can be made to procedures. Seven key recommendations are made to further develop capability and enhance the collaboration between the volcano observatory, volcano research institutions and civil protection authorities. These recommendations cover topics including notification of responders, authoritative messaging, data sharing and media interaction, and are more broadly applicable to volcanic institutions elsewhere. Lessons and suggestions for how to run a large-scale volcanic exercise are given and could be adopted by those planning to rehearse their own response procedures.

scholarly journals Potential impacts of tephra fallout from a large-scale explosive eruption at Sakurajima volcano, Japan

2017 ◽  
Vol 79 (10) ◽  
Author(s):  
S. Biass ◽  
A. Todde ◽  
R. Cioni ◽  
M. Pistolesi ◽  
N. Geshi ◽  
...  
Keyword(s):  
Large Scale ◽  
Explosive Eruption ◽  
Sakurajima Volcano ◽  
Tephra Fallout

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

Some applications of electron beam microanalysis techniques in VLSI process evaluation

1983 ◽  
Vol 41 ◽  
pp. 160-161
Author(s):  
Simon Thomas
Keyword(s):  
Integrated Circuits ◽  
Process Evaluation ◽  
Large Scale ◽  
Technology Development ◽  
Analytical Techniques ◽  
Successful Implementation ◽  
Analysis Of Failures ◽  
Characterization Of Materials ◽  
Circuits Vlsi

Trends in the technology development of very large scale integrated circuits (VLSI) have been in the direction of higher density of components with smaller dimensions. The scaling down of device dimensions has been not only laterally but also in depth. Such efforts in miniaturization bring with them new developments in materials and processing. Successful implementation of these efforts is, to a large extent, dependent on the proper understanding of the material properties, process technologies and reliability issues, through adequate analytical studies. The analytical instrumentation technology has, fortunately, kept pace with the basic requirements of devices with lateral dimensions in the micron/ submicron range and depths of the order of nonometers. Often, newer analytical techniques have emerged or the more conventional techniques have been adapted to meet the more stringent requirements. As such, a variety of analytical techniques are available today to aid an analyst in the efforts of VLSI process evaluation. Generally such analytical efforts are divided into the characterization of materials, evaluation of processing steps and the analysis of failures.

Electron microscopy study of reactively sputter-deposited Ti/N films on silicon

1992 ◽  
Vol 50 (2) ◽  
pp. 1362-1363
Author(s):  
V. C. Kannan ◽  
A. K. Singh ◽  
R. B. Irwin ◽  
S. Chittipeddi ◽  
F. D. Nkansah ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Large Scale ◽  
Hexagonal Phase ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Process Conditions ◽  
Tin Films ◽  
Wide Range ◽  
Fcc Phase ◽  
Circuits Vlsi

Titanium nitride (TiN) films have historically been used as diffusion barrier between silicon and aluminum, as an adhesion layer for tungsten deposition and as an interconnect material etc. Recently, the role of TiN films as contact barriers in very large scale silicon integrated circuits (VLSI) has been extensively studied. TiN films have resistivities on the order of 20μ Ω-cm which is much lower than that of titanium (nearly 66μ Ω-cm). Deposited TiN films show resistivities which vary from 20 to 100μ Ω-cm depending upon the type of deposition and process conditions. TiNx is known to have a NaCl type crystal structure for a wide range of compositions. Change in color from metallic luster to gold reflects the stabilization of the TiNx (FCC) phase over the close packed Ti(N) hexagonal phase. It was found that TiN (1:1) ideal composition with the FCC (NaCl-type) structure gives the best electrical property.

Evolution of the microstructure of Cu(Ti)/SiO2 layers annealed in NH3

1995 ◽  
Vol 53 ◽  
pp. 452-453
Author(s):  
J. Liu ◽  
N. D. Theodore ◽  
D. Adams ◽  
S. Russell ◽  
T. L. Alford ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Titanium Nitride ◽  
Large Scale ◽  
Standard Procedure ◽  
Alloy Film ◽  
Electron Beam Evaporation ◽  
Copper Metallization ◽  
Nominal Composition ◽  
Ti Alloy ◽  
Thermally Grown

Copper-based metallization has recently attracted extensive research because of its potential application in ultra-large-scale integration (ULSI) of semiconductor devices. The feasibility of copper metallization is, however, limited due to its thermal stability issues. In order to utilize copper in metallization systems diffusion barriers such as titanium nitride and other refractory materials, have been employed to enhance the thermal stability of copper. Titanium nitride layers can be formed by annealing Cu(Ti) alloy film evaporated on thermally grown SiO2 substrates in an ammonia ambient. We report here the microstructural evolution of Cu(Ti)/SiO2 layers during annealing in NH3 flowing ambient.The Cu(Ti) films used in this experiment were prepared by electron beam evaporation onto thermally grown SiO2 substrates. The nominal composition of the Cu(Ti) alloy was Cu73Ti27. Thermal treatments were conducted in NH3 flowing ambient for 30 minutes at temperatures ranging from 450°C to 650°C. Cross-section TEM specimens were prepared by the standard procedure.

Immunogold labeling of CMP-KDO synthetase produced by recombinant E. Coli cells

1987 ◽  
Vol 45 ◽  
pp. 924-925
Author(s):  
F. A. Durum ◽  
R. G. Goldman ◽  
T. J. Bolling ◽  
M. F. Miller
Keyword(s):  
Inclusion Bodies ◽  
Large Scale ◽  
Recombinant Dna ◽  
Test System ◽  
Cell Protein ◽  
Gram Negative Bacteria ◽  
Cytoplasmic Inclusions ◽  
Isolation And Purification ◽  
E Coli ◽  
Low Concentrations

CMP-KDO synthetase (CKS) is an enzyme which plays a key role in the synthesis of LPS, an outer membrane component unique to gram negative bacteria. CKS activates KDO to CMP-KDO for incorporation into LPS. The enzyme is normally present in low concentrations (0.02% of total cell protein) which makes it difficult to perform large scale isolation and purification. Recently, the gene for CKS from E. coli was cloned and various recombinant DNA constructs overproducing CKS several thousandfold (unpublished data) were derived. Interestingly, no cytoplasmic inclusions of overproduced CKS were observed by EM (Fig. 1) which is in contrast to other reports of large proteinaceous inclusion bodies in various overproducing recombinant strains. The present immunocytochemical study was undertaken to localize CKS in these cells.Immune labeling conditions were first optimized using a previously described cell-free test system. Briefly, this involves soaking small blocks of polymerized bovine serum albumin in purified CKS antigen and subjecting them to various fixation, embedding and immunochemical conditions.

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