scholarly journals Volcanology and inflation structures of an extensive basaltic lava flow in the Payenia Volcanic Province, extra-Andean back arc of Argentina

2019 ◽  
Vol 46 (2) ◽  
pp. 279 ◽  
Author(s):  
Mauro Ignacio Bernardi ◽  
Gustavo Walter Bertotto ◽  
Alexis Daniel Ponce ◽  
Yuji Orihashi ◽  
Hirochika Sumino
Keyword(s):  
Lava Flow ◽  
Liquid Core ◽  
Internal Flow ◽  
Middle Pleistocene ◽  
High Concentration ◽  
Volcanic Province ◽  
Low Viscosity ◽  
Effusion Rates ◽  
Flow Pathways ◽  
P Type

The El Puesto lava flow is located in the Payenia Volcanic Province (central-western Argentina), has a length of 70 km and is Middle Pleistocene in age (0.200±0.027 Ma). The flow shows a P-type pahoehoe structure and exhibits several inflation structures, mainly tumuli and also inflation ridges and lava rises. Lava rise pits and radial or annular clefts are common features associated with inflation structures. The gentle slope on which the flow moved (≈0.5°) allowed the lateral coalescence of lobes at the flow front and the development of an external rigid crust that insulated the liquid core. Lava tunnels are frequent and the lava tunnel named “Cueva de Halada” which is located at its medium portion is the best example of a drainage master tube which formed from the cooling of the crust around a stable inflated flow. Tumuli alignments and long inflation ridges reveal the existence of larger tunnels within the flow. Inflation structures may occur in high concentration belts that converge on a single main belt which is assigned to an anastomosed network of internal flow pathways within the main lava body. The development of inflation structures and lava tunnels require low to moderate effusion rates. An average lava supply rate of 1.8x10-4 m3/s and an inflation time of about 15 days were estimated for an average tumulus of this flow. A high and sustained supply of low viscosity lava (η’=1550 - 483 Pa s) was inferred that initially generated a sheet flow of great areal extension. The reduction in effusion rates could then allowed the development of tunnels that carried lava to the distal fronts, generating localized inflation phenomena throughout the lava flow.

scholarly journals Simple empirical method for estimating lava-effusion rate using nighttime Himawari-8 1.6-µm infrared images

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Takayuki Kaneko ◽  
Atsushi Yasuda ◽  
Toshitsugu Fujii
Keyword(s):  
Lava Flow ◽  
Estimation Method ◽  
Simulation Software ◽  
Spectral Radiance ◽  
Effusion Rate ◽  
Actual Distribution ◽  
High Positive Correlation ◽  
Low Viscosity ◽  
Lava Effusion ◽  
The Relationship

AbstractThe effusion rate of lava is one of the most important eruption parameters, as it is closely related to the migration process of magma underground and on the surface, such as changes in lava flow direction or formation of new effusing vents. Establishment of a continuous and rapid estimation method has been an issue in volcano research as well as disaster prevention planning. For effusive eruptions of low-viscosity lava, we examined the relationship between the nighttime spectral radiance in the 1.6-µm band of the Himawari-8 satellite (R1.6Mx: the pixel value showing the maximum radiance in the heat source area) and the effusion rate using data from the 2017 Nishinoshima activity. Our analysis confirmed that there was a high positive correlation between these two parameters. Based on the linear-regression equation obtained here (Y = 0.47X, where Y is an effusion rate of 106 m3 day−1 and X is an R1.6Mx of 106 W m−2 sr−1 m−1), we can estimate the lava-effusion rate from the observation data of Himawari-8 via a simple calculation. Data from the 2015 Raung activity—an effusive eruption of low-viscosity lava—were arranged along the extension of this regression line, which suggests that the relationship is applicable up to a level of ~ 2 × 106 m3 day−1. We applied this method to the December 2019 Nishinoshima activity and obtained an effusion rate of 0.50 × 106 m3 day−1 for the initial stage. We also calculated the effusion rate for the same period based on a topographic method, and verified that the obtained value, 0.48 × 106 m3 day−1, agreed with the estimation using the Himawari-8 data. Further, for Nishinoshima, we simulated the extent of hazard areas from the initial lava flow and compared cases using the effusion rate obtained here and the value corresponding to the average effusion rate for the 2013–2015 eruptions. The former distribution was close to the actual distribution, while the latter was much smaller. By combining this effusion-rate estimation method with real-time observations by Himawari-8 and lava-flow simulation software, we can build a rapid and precise prediction system for volcano hazard areas.

Lava flow eruption conditions in the Tharsis Volcanic Province on Mars

2021 ◽  
Author(s):  
Sean Peters ◽  
Philip Russel Christensen ◽  
Amanda B Clarke
Keyword(s):  
Lava Flow ◽  
Volcanic Province

scholarly journals Supplemental Material: Linking lava morphologies to effusion rates for the 2014–2015 Holuhraun lava flow field, Iceland

2021 ◽  
Author(s):  
Joana R. C. Voigt ◽  
et al.
Keyword(s):  
Flow Field ◽  
Lava Flow ◽  
Lava Flow Field ◽  
Effusion Rates

Details about previous established links between emplacement conditions and lava types, data and methods, additional correlation results, and limitations.<br>

Effects of polymers concentration on EHL film-forming in point contacts

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liangwei Qiu ◽  
Xiaoyang Chen ◽  
Fakai Dong
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Point Contact ◽  
High Concentration ◽  
Content Type ◽  
Base Oils ◽  
Low Viscosity ◽  
Lubricant Oil ◽  
Pure Rolling ◽  
Film Forming

Purpose This paper aims to experimentally investigate the film-forming capability of base oils containing poly-methacrylate (PMA) and poly-isobutene (PIB), in a point contact under pure rolling. Design/methodology/approach By using the relative light intensity method, the film thickness is calculated from the interferometer images which are captured by multiple-contact optical elastohydrodynamic lubricated test rig. Findings The test results reveal that polymers, both PMA and PIB, have a significant contribution to the film-forming capability of base oils and the film thickness increases with concentration. The forming-film capabilities for PMA and PIB in base oils are similar at low concentration, while PIB gives a higher film thickness than PMA at high concentration. Shear-thinning phenomenon are observed in all polymer-based oils. Originality/value The polymer usually as an additive is added into the low viscosity base oils to improve the properties of lubricant oil. This paper reports the lubricated properties of PMA and PIB with different concentrations in base oils and to evaluate their functional mechanism in a point contact. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0263/

scholarly journals Comparison of Strategies in Development and Manufacturing of Low Viscosity, Ultra-High Concentration Formulation for IgG1 Antibody

2020 ◽  
Vol 109 (12) ◽  
pp. 3579-3589
Author(s):  
Vaibhav Deokar ◽  
Alok Sharma ◽  
Rustom Mody ◽  
Subrahmanyam M. Volety
Keyword(s):  
High Concentration ◽  
Igg1 Antibody ◽  
Low Viscosity

Stability analysis of a particle band on the fluid–fluid interface

2019 ◽  
Vol 869 ◽  
Author(s):  
Alireza Hooshanginejad ◽  
Benjamin C. Druecke ◽  
Sungyon Lee
Keyword(s):  
Stability Analysis ◽  
Colloidal Particles ◽  
Radial Flow ◽  
High Viscosity ◽  
High Concentration ◽  
Stable Suspension ◽  
Low Viscosity ◽  
Air Interface ◽  
Critical Wavelength ◽  
Hele Shaw Cell

We present experiments and theory for viscous fingering of a suspension of non-colloidal particles undergoing radial flow in a Hele-Shaw cell. As the suspension displaces air, shear-induced migration causes particles to move faster than the average suspension velocity and to accumulate on the suspension–air interface. The resultant particle accumulation generates a pattern in which low-concentration, low-viscosity suspension displaces high-concentration, high-viscosity suspension and is unstable due to the classic Saffman–Taylor instability mechanism. While the destabilising mechanism is well-understood, what remains unknown is the stabilising mechanism that suppresses fine fingers characteristic of miscible fingering. In this work, we demonstrate how the stable suspension–air interface interacts with the unstable miscible interface to set the critical wavelength. We present a linear stability analysis for the time-dependent radial flow and show that the wavenumber predicted by the analysis is in good agreement with parametric experiments investigating the effect of suspension concentration and gap thickness of the Hele-Shaw cell.

scholarly journals Diffusion Timescales of Magmatic Processes in the Moinui Lava Eruption at Mauna Loa, Hawai`i, as Inferred from Bimodal Olivine Populations

2020 ◽  
Vol 61 (7) ◽  
Author(s):  
F K Couperthwaite ◽  
T Thordarson ◽  
D J Morgan ◽  
J Harvey ◽  
M Wilson
Keyword(s):  
Lava Flow ◽  
Storage Conditions ◽  
Magma Storage ◽  
Mauna Loa ◽  
Low Viscosity ◽  
Lava Flow Field ◽  
Magmatic Processes ◽  
Geochemical Variations ◽  
And Storage ◽  
Time Information

Abstract The 2·1 ka Moinui lava flow field, erupted from the southwest rift zone of Mauna Loa, Hawai`i, exhibits striking textural and geochemical variations, that can be used to interpret magma processes pre-, syn- and post-eruption. From this lava flow, the duration of magma storage and storage conditions, the timescales over which magma is transported to the surface, and flow emplacement mechanisms at Mauna Loa are determined. Electron microprobe analysis (EMPA) and diffusion chronometry of olivine crystals identify two distinct crystal populations: a primitive, polyhedral olivine population with core compositions of Fo90–88 and a more evolved, platy olivine population with core compositions of Fo83–82. Fe–Mg diffusion modelling of these olivine populations gives distinct timescales for each population; platy olivines yield timescales of days up to a few weeks, while polyhedral olivines yield timescales of months to years. Despite the nature of a well-insulated pāhoehoe flow, meaning that post-emplacement diffusion continues for some time, a wealth of time information can be retrieved concerning pre-eruptive magmatic processes as well as the processes associated with the lava extrusion. The short timescales obtained from the platy olivine crystals and the observed equilibrium between its cores and ambient melt suggest late-stage nucleation and crystal growth in the shallow conduit and during lava emplacement. Conversely, the longer timescales and olivine-melt disequilibrium of the polyhedral olivine crystals suggests accumulation from a deeper source and subsequent transportation to shallow magma storage beneath the summit of Mauna Loa months, or even years before eruption. The chemical and textural details of the Moinui lava reflect the mode of flow emplacement and may have implications for the interpretation of the distribution of spinifex and cumulate olivine within komatiites; high-temperature, low-viscosity lavas, common in the Archean.

MEDICAL APPLICATIONS OF PARTICLE-INDUCED X-RAY EMISSION

2008 ◽  
Vol 18 (03n04) ◽  
pp. 101-110
Author(s):  
S. HARADA ◽  
S. EHARA ◽  
K. ISHII ◽  
H. YAMAZAKI ◽  
S. MATSUYAMA ◽  
...  
Keyword(s):  
Anticancer Drug ◽  
Liquid Core ◽  
Medical Applications ◽  
High Concentration ◽  
Antitumor Effects ◽  
X Ray ◽  
Core Content ◽  
Dependent Endonuclease ◽  
Radiation Induced ◽  
Induced Apoptosis

We report two medical applications of particle-induced X-ray emission (PIXE) as described below (1) Observation of biological events: The kinetics of trace elements during the initiation of radiation-induced apoptosis (RIA) was observed using a micro-PIXE and PIXE. RIA is a process in which irradiated cells commit suicide; it results in the removal of severely damaged and harmful cells. During RIA, cytochrome c is released from the mitochondria and reaches the nucleus, where it activates a Ca- or Mg-dependent endonuclease. We examined this phenomenon by using a micro-PIXE and PIXE. A high concentration of Fe was detected in the stroma of cells in the early apoptotic phase. We also observed accumulation of large amounts of Ca and Mg in the nucleus.(2) Development of liquid-core microcapsules for novel cancer chemoradiotherapy: Currently, we are developing liquid-core (containing an anticancer drug) microcapsules that release their core content upon irradiation. These microcapsules will localize the anticancer drug within the irradiated field. The outer shell of these microcapsules is prepared from alginate and hyaluronic acid and polymerized by Fe, while the anticancer drug Paraplatin®(carboplatin) containing Pt is the liquid core. The micro-PIXE revealed that these microcapsules released their core content after irradiation, and the amount of carboplatin released was measured by PIXE. More than 83.1% ± 8.3% of the microcapsules were ruptured, and the amount of carboplatin released was more than 81.2% ± 2.3%. Thus, the combination of radiotherapy and chemotherapy showed improved antitumor effects and a decrease in adverse effects because of drug localization.

Mount Etna and the 1971 eruption - Lengths of lava flows

1973 ◽  
Vol 274 (1238) ◽  
pp. 107-118 ◽  
Keyword(s):  
Lava Flow ◽  
High Viscosity ◽  
Lava Flows ◽  
Mount Etna ◽  
High Rate ◽  
Low Viscosity ◽  
Depression Measurement ◽  
Lateral Extent ◽  
The One ◽  
Single Flow

The principal factor influencing the length of a lava flow is the rate of effusion. With a high rate the lava flows rapidly from the source and tends to form an extensive and far-reaching flow which is simple in character (i.e. made of a single flow unit). With a low rate the lava tends to pile up layer upon layer to form a local accumulation of limited lateral extent near the source, and this accumulation is strongly compound in character (i.e. divisible into flow units). The initial viscosity affects the length indirectly by controlling the thickness of the extrusion, and this thickness control is capable of accounting for the fact that the median length of low-viscosity basaltic extrusions is 3.2 times that of high-viscosity andesite, trachyte and rhyolite ones. Other factors, such as the local topography, are thought to be relatively unimportant, an exception being when lava is ponded in a topographic depression. Measurement of the rate of effusion may be critical in any attempt to predict the distance that a lava flow will travel, such as the one which threatened Fornazzo and other towns and villages on Etna in 1971.

Emplacement history of a low-viscosity, fountain-fed pantelleritic lava flow

1993 ◽  
Vol 57 (1-2) ◽  
pp. 39-56 ◽  
Author(s):  
Richard J. Stevenson ◽  
Roger M. Briggs ◽  
A.Peter W. Hodder
Keyword(s):  
Lava Flow ◽  
Low Viscosity ◽  
History Of
Sign in / Sign up

Export Citation Format

Share Document