scholarly journals Ascent velocity and dynamics of the Fiumicino mud eruption, Rome, Italy

2015 ◽  
Vol 42 (15) ◽  
pp. 6244-6252 ◽  
Author(s):  
A. Vona ◽  
G. Giordano ◽  
A. A. De Benedetti ◽  
R. D'Ambrosio ◽  
C. Romano ◽  
...  
Keyword(s):  
Ascent Velocity

Climbing Performance in U23 and Professional Cyclists during a Multi-stage Race

2021 ◽  
Author(s):  
Peter Leo ◽  
James Spragg ◽  
Dieter Simon ◽  
Justin Lawley ◽  
Iñigo Mujika
Keyword(s):  
Power Output ◽  
Performance Metrics ◽  
Study Data ◽  
Intensity Measures ◽  
Multi Stage ◽  
Road Cycling ◽  
Ascent Velocity ◽  
Race Performance

AbstractThe aim of this study was to analyze climbing performance across two editions of a professional multistage race, and assess the influence of climb category, prior workload, and intensity measures on climbing performance in U23 and professional cyclists. Nine U23 cyclists (age 20.8±0.9 years) and 8 professional cyclists (28.1±3.2 years) participated in this study. Data were divided into four types: overall race performance, climb category, climbing performance metrics (power output, ascent velocity, speed), and workload and intensity measures. Differences in performance metrics and workload and intensity measures between groups were investigated. Power output, ascent velocity, speed were higher in professionals than U23 cyclists for Cat 1 and Cat 2 (p≤0.001–0.016). Workload and intensity measures (Worktotal, Worktotal∙km-1, Elevationgain, eTRIMP and eTRIMP∙km-1) were higher in U23 compared to professionals (p=0.002–0.014). Climbing performance metrics were significantly predicted by prior workload and intensity measures for Cat 1 and 2 (R2=0.27–0.89, p≤0.001–0.030) but not Cat 3. These findings reveal that climbing performance in professional road cycling is influenced by climb categorization as well as prior workload and intensity measures. Combined, these findings suggest that Cat 1 and 2 climbing performance could be predicted from workload and intensity measures.

Gas diffusion from ascending gas bubbles

1969 ◽  
Vol 35 (4) ◽  
pp. 711-719 ◽  
Author(s):  
Paul H. Leblond
Keyword(s):  
Surface Tension ◽  
Gas Exchange ◽  
Gas Bubbles ◽  
Gas Diffusion ◽  
Gas Pressure ◽  
Pressure Balance ◽  
Spherical Bubble ◽  
Gas Leakage ◽  
Quantitative Results ◽  
Ascent Velocity

General qualitative rules are derived for the behaviour of the volume of an ascending spherical bubble and of the gas pressure within it. Three modes of behaviour are discerned, corresponding to as many possible orderings of the relative influences of ascent velocity, gas leakage and surface tension on the volume and the pressure balance. These general results are nearly independent of the particular forms of the ascent velocity and gas exchange functions. Quantitative results are presented for the Stokes law régime.

scholarly journals Episodic transport of discrete magma batches beneath Aso volcano

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jieming Niu ◽  
Teh-Ru Alex Song
Keyword(s):  
Normal Fault ◽  
Magma Ascent ◽  
Aso Volcano ◽  
Storage Pool ◽  
Brittle Ductile Transition ◽  
Deformation Event ◽  
Deep Reservoir ◽  
Ascent Velocity ◽  
A Minor

AbstractMagma ascent, storage, and discharge in the trans-crustal magmatic system are keys to long-term volcanic output and short-term eruption dynamics. How a distinct magma batch transports from a deep reservoir(s) to a pre-eruptive storage pool with eruptible magma remains elusive. Here we show that repetitive very-long-period signals (VLPs) beneath the Aso volcano are preceded by a short-lived (~50–100 s), synchronous deformation event ~3 km apart from the VLP source. Source mechanism of a major volumetric component (~50–440 m3 per event) and a minor low-angle normal-fault component, together with petrological evidence, suggests episodic transport of discrete magma batches from an over-pressured chamber roof to a pre-eruptive storage pool near the brittle-ductile transition regime. Magma ascent velocity, decompression rate, and cumulative magma output deduced from recurrent deformation events before recent 2014 and 2016 eruptions reconcile retrospective observations of the eruption style, tephra fallouts, and plume heights, promising real-time evaluation of upcoming eruptions.

scholarly journals Modeling the Crystallization and Emplacement Conditions of a Basaltic Trachyandesitic Sill at Mt. Etna Volcano

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 126 ◽  
Author(s):  
Manuela Nazzari ◽  
Flavio Di Stefano ◽  
Silvio Mollo ◽  
Piergiorgio Scarlato ◽  
Vanni Tecchiato ◽  
...  
Keyword(s):  
Lattice Strain ◽  
Magma Ascent ◽  
Stability Field ◽  
Etna Volcano ◽  
Mt Etna ◽  
Ascent Velocity ◽  
Compositional Variations ◽  
Kinetic Effects ◽  
Lower Temperature ◽  
The Stability

This study documents the compositional variations of phenocrysts from a basaltic trachyandesitic sill emplaced in the Valle del Bove at Mt. Etna volcano (Sicily, Italy). The physicochemical conditions driving the crystallization and emplacement of the sill magma have been reconstructed by barometers, oxygen barometers, thermometers and hygrometers based on clinopyroxene, feldspar (plagioclase + K-feldspar) and titanomagnetite. Clinopyroxene is the liquidus phase, recording decompression and cooling paths decreasing from 200 to 0.1 MPa and from 1050 to 940 °C, respectively. Plagioclase and K-feldspar cosaturate the melt in a lower temperature interval of ~1000–870 °C. Cation exchanges in clinopyroxene (Mg-Fe) and feldspar (Ca-Na) indicate that magma ascent is accompanied by progressive H2O exsolution (up to ~2.2 wt. %) under more oxidizing conditions (up to ΔNNO + 0.5). Geospeedometric constraints provided by Ti–Al–Mg cation redistributions in titanomagnetite indicate that the travel time (up to 23 h) and ascent velocity of magma (up to 0.78 m/s) are consistent with those inferred for other eruptions at Mt. Etna. These kinetic effects are ascribed to a degassing-induced undercooling path caused principally by H2O loss at shallow crustal conditions. Rare earth element (REE) modeling based on the lattice strain theory supports the hypothesis that the sill magma formed from primitive basaltic compositions after clinopyroxene (≤41%) and plagioclase (≤12%) fractionation. Early formation of clinopyroxene at depth is the main controlling factor for the REE signature, whereas subsequent degassing at low pressure conditions enlarges the stability field of plagioclase causing trace element enrichments during eruption towards the surface.

Creeping plumes

1985 ◽  
Vol 158 ◽  
pp. 511-531 ◽  
Author(s):  
Peter Olson ◽  
Harvey Singer
Keyword(s):  
Viscous Fluid ◽  
Scaling Laws ◽  
Glucose Solution ◽  
Hot Spot ◽  
Source Parameters ◽  
Fluid Viscosity ◽  
Ambient Fluid ◽  
Buoyant Plumes ◽  
Ascent Rate ◽  
Ascent Velocity

Results of laboratory experiments are used to determine the morphology and the ascent rate of growing buoyant plumes in a homogeneous, viscous fluid. The plumes were formed by injecting a glucose solution through a small orifice into another glucose solution of different density. Two classes of creeping (low-Reynolds-number) plumes are investigated: (i) diapiric plumes, for which the plume viscosity is approximately equal to the ambient-fluid viscosity, and (ii) cavity plumes, for which the plume fluid is much less viscous than the ambient fluid. Fully developed diapirs consist of a tapered cylindrical stem capped by a mushroom-shaped vortex at its leading edge. Fully developed cavity plumes consist of a nearly spherical chamber connected to the source by a narrow umbilical conduit. It is observed that the ascent velocity of cavity plumes increases with time as t⅖. The ascent velocity of diapirs is found to be proportional to the terminal velocity of a cylinder moving parallel to its axis. The presence of pre-existing conduits alters the morphology of cavity plumes and greatly increases their ascent rate. Fossil conduits act as plume guides by offering low-resistance ascent paths. Finally, a series of experiments have been made on the interaction between cavity plumes and a large-scale background circulation. A low-viscosity plume generated by a source towed steadily through a highly viscous fluid breaks into a chain of regularly spaced, individual cavities, as first demonstrated by Skilbeck & Whitehead. The cavities ascend as an inclined linear array of Stokes droplets. Dimensional analysis is used to derive scaling laws for the cavity volumes and their replication rate in terms of the source parameters and the tow speed. The qualitative results from these experiments generally lend support to the hypothesis that buoyant plumes in the Earth's mantle are the source of hot-spot volcanism. In particular the experiments suggest an explanation for the observation that hot spots remain nearly fixed in the presence of mantle convection.

Tholeiite, alkali basalt and ascent velocity

Nature ◽  
1974 ◽  
Vol 252 (5478) ◽  
pp. 31-32 ◽  
Author(s):  
CLAUDE J. ALLEGRE ◽  
YAN BOTTINGA
Keyword(s):  
Alkali Basalt ◽  
Ascent Velocity

scholarly journals GEODYNAMIC PROCESSES DURING ASCENT OF A PLUME WITH INTERMEDIATE THERMAL POWER THROUGH THE CONTINENTAL LITHOSPHERE AND DURING ITS ERUPTION ON THE SURFACE

2020 ◽  
Vol 11 (2) ◽  
pp. 397-416
Author(s):  
A. G. Kirdyashkin ◽  
A. A. Kirdyashkin ◽  
V. E. Distanov ◽  
I. N. Gladkov
Keyword(s):  
Flow Structure ◽  
Dynamic Pressure ◽  
Thermal Power ◽  
Ground Surface ◽  
Continental Lithosphere ◽  
Laboratory Modeling ◽  
Geodynamic Processes ◽  
Plane Passing ◽  
Ascent Velocity ◽  
Modeling Data

The study is focused on thermochemical mantle plumes with intermediate thermal power (1.15 < Ka < 1.9). Previously we have shown that these plumes are diamondiferous. Based on the laboratory modeling data, the flow structure of a melt in a plume conduit is represented. A plume melts out and ascends from the core – mantle boundary to the bottom of the continental lithosphere. The plume roof moves upwards in the lithosphere because of melting of the lithospheric matter at the plume roof and due to the effect of superlithostatic pressure on the roof, which causes motion in the lithosphere block above the plume roof. The latter manifests itself by uplifting of the ground surface above the plume. As the plume ascends through the lithosphere, the elevation of the surface increases until the plume ascends to critical level xкр, where an eruption conduit is formed. In our model, plume ascent velocity uпл is the rate of melting at the plume roof. Values of uпл and the ascent velocity of a spherical plume roof due to superlithostatic pressure U are calculated. Relationships are found between these velocities and the plume roof depth. The dependence of the velocity of the surface’s rise on the dynamic viscosity of the lithosphere block above the plume is obtained. A relationship is determined between the maximum surface elevation and the lithosphere viscosity. The elevation values are determined for different times and different lithosphere viscosities.The results of laboratory modeling of flow structure at the plume conduit/eruption conduit interface are presented. The flow was photographed (1) in the plane passing through the axes of the plume conduit and the eruption conduit; and (2) in case of the line-focus beam perpendicular to the axial plane. The photographs were used for measuring the flow velocities in the plume conduit and the eruption conduit. Corresponding Reynolds numbers and flow regimes are determined. The relation of dynamic pressure in the eruption conduit to that in the plume conduit is found for intermediate-power plumes. The melt flow velocity in the eruption conduit depends on superlithostatic pressure on the plume roof, plume diameter and kinematic viscosity of the melt. Its values are determined for different kinematic viscosities of melt.

Buoyancy-driven crack propagation: a mechanism for magma migration

1987 ◽  
Vol 174 ◽  
pp. 135-153 ◽  
Author(s):  
D. A. Spence ◽  
P. W. Sharp ◽  
D. L. Turcotte
Keyword(s):  
Differential Equation ◽  
Eigenfunction Expansion ◽  
Constant Width ◽  
Optimization Technique ◽  
Propagation Speed ◽  
Nonlinear Constrained Optimization ◽  
Earth’S Mantle ◽  
Ascent Velocity ◽  
Steady Propagation ◽  
Magma Migration

A solution has been obtained for steady propagation of a two-dimensional fluid fracture driven by buoyancy in an elastic medium. The problem is formulated in terms of an integro-differential equation governing the elastic deformation, coupled with the differential equation of lubrication theory for viscous flow in the crack. The numerical treatment of this system is carried out in terms of an eigenfunction expansion of the cavity shape, in which the coefficients are found by use of a nonlinear constrained optimization technique. When suitably non-dimensionalized, the solution appears to be unique. It exhibits a semi-infinite crack of constant width following the propagating fracture. For each value of the stress intensity factor of the medium, the width and propagation speed are determined. The results are applied to the problem of the vertical ascent of magma through the earth's mantle and crust. Values obtained for the crack width and ascent velocity are in accord with observations. This mechanism can explain the high ascent velocities required to quench diamonds during a Kimberlite eruption. The mechanism can also explain how basaltic eruptions can carry large mantle rocks (xenoliths) to the surface.

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