An overview of the global variability in radiated energy and apparent stress

2006 ◽  
pp. 43-57 ◽  
Author(s):  
George L. Choy ◽  
Art McGarr ◽  
Stephen H. Kirby ◽  
John Boatwright
Keyword(s):  
Apparent Stress ◽  
Radiated Energy

Far-field radiated energy scaling in elastodynamic earthquake fault models

1998 ◽  
Vol 88 (6) ◽  
pp. 1457-1465
Author(s):  
Bruce E. Shaw
Keyword(s):  
Stress Drop ◽  
Field Energy ◽  
Far Field ◽  
Apparent Stress ◽  
Fault Models ◽  
Conservation Of Energy ◽  
Rupture Length ◽  
Radiated Energy ◽  
Sequence Of Events ◽  
Wide Range

Abstract Measurements of the far-field radiated energy in very simple elastodynamic fault models is presented, and the scaling of the radiated energy with moment and rupture length is examined. The models produce a complex sequence of events having a wide range of sizes as a result of a frictional-weakening instability. Thus, radiated energy from a broad range of sizes of events can be measured. Using conservation of energy, I am able to measure the far-field energy very accurately and efficiently. I study a range of frictions, from velocity weakening to slip weakening, in order to examine the effects of the physics of the rupture source on the radiated energy. Examining the scaling of radiated energy as a function of moment and rupture length, I find differences for slip-weakening as compared to velocity-weakening friction. I find distinct differences in how the apparent stress scales with moment and also how the apparent stress divided by the stress drop scales with moment for the different frictions. Most dramatically, the apparent stress divided by the stress drop is significantly smaller for slip weakening relative to velocity weakening. This suggests that measurements of radiated energy versus moment and rupture length in earthquakes, combined with forward elastodynamic modeling, can be used to constrain possible source physics.

scholarly journals Topological complexity of frictional interfaces: friction networks

2012 ◽  
Vol 19 (2) ◽  
pp. 215-225 ◽  
Author(s):  
H. O. Ghaffari ◽  
R. P. Young
Keyword(s):  
Topological Complexity ◽  
Type Ii ◽  
Stored Energy ◽  
Fracture Permeability ◽  
Radiated Energy ◽  
Universal Power Law ◽  
Shear Rupture ◽  
Crack Type ◽  
Network Properties ◽  
Highly Correlated

Abstract. Through research conducted in this study, a network approach to the correlation patterns of void spaces in rough fractures (crack type II) was developed. We characterized friction networks with several networks characteristics. The correlation among network properties with the fracture permeability is the result of friction networks. The revealed hubs in the complex aperture networks confirmed the importance of highly correlated groups to conduct the highlighted features of the dynamical aperture field. We found that there is a universal power law between the nodes' degree and motifs frequency (for triangles it reads T(k) ∝ kβ (β ≈ 2 ± 0.3)). The investigation of localization effects on eigenvectors shows a remarkable difference in parallel and perpendicular aperture patches. Furthermore, we estimate the rate of stored energy in asperities so that we found that the rate of radiated energy is higher in parallel friction networks than it is in transverse directions. The final part of our research highlights 4 point sub-graph distribution and its correlation with fluid flow. For shear rupture, we observed a similar trend in sub-graph distribution, resulting from parallel and transversal aperture profiles (a superfamily phenomenon).

On the scale dependence in the dynamics of rupture

2021 ◽  
Author(s):  
Federica Paglialunga ◽  
François Passelègue ◽  
Fabian Barras ◽  
Mathias Lebihain ◽  
Nicolas Brantut ◽  
...  
Keyword(s):  
Large Scale ◽  
Cohesive Zone Model ◽  
Experimental Studies ◽  
Stress Singularity ◽  
Scale Dependence ◽  
Zone Model ◽  
Stick Slip ◽  
Radiated Energy ◽  
Rupture Energy ◽  
Natural Earthquakes

<p>Potential energy stored during the inter-seismic period by tectonic loading around faults can be released through earthquakes as radiated energy, heat and rupture energy. The latter is of first importance, since it controls both the nucleation and the propagation of the seismic rupture. On one side, the rupture energy estimated for natural earthquakes (also called Breakdown work) ranges between 1 J/m<sup>2</sup> and tens of MJ/m<sup>2</sup> for the largest events, and shows a clear slip dependence. On the other side, recent experimental studies highlighted that at the scale of the laboratory, rupture energy is a material property (energy required to break the fault interface), limited by an upper bound value corresponding to the rupture energy of the intact material (1 to 10 kJ/m<sup>2</sup>), independently of the size of the event, i.e. of the seismic slip.</p><p>To reconcile these contradictory observations, we performed stick-slip experiments, as an analog for earthquakes, in a bi-axial shear configuration. We analyzed the fault weakening during frictional rupture by accessing to the on-fault (1 mm away) stress-slip curve through strain-gauge array. We first estimated rupture energy by comparing the experimental strain with the theoretical predictions from both Linear Elastic Fracture Mechanics (LEFM) and the Cohesive Zone Model (CZM). Secondly, we compared these values to the breakdown work obtained from the integration of the stress-slip curve. Our results showed that, at the scale of our experiments, fault weakening is divided into two stages; the first one, corresponding to an energy of few J/m<sup>2</sup>, coherent with the estimated rupture energy (by LEFM and CZM), and a long-tailed weakening corresponding to a larger energy not observable at the rupture tip.</p><p>Using a theoretical analysis and numerical simulations, we demonstrated that only the first weakening stage controls the nucleation and the dynamics of the rupture tip. The breakdown work induced by the long-tailed weakening can enhance slip during rupture propagation and can allow the rupture to overcome stress heterogeneity along the fault. Additionally, we showed that at a large scale of observation the dynamics of the rupture tip can become controlled by the breakdown work induced by the long-tailed weakening, leading to a larger stress singularity at the rupture tip which becomes less sensitive to stress perturbations. We suggest that while the onset of frictional motions is related to fracture, natural earthquakes propagation is driven by frictional weakening with increasing slip, explaining the large values of estimated breakdown work for natural earthquakes, as well as the scale dependence in the dynamics of rupture.</p>

Thermonuclear plasma conditions in stellar interiors

1981 ◽  
Vol 300 (1456) ◽  
pp. 641-648
Keyword(s):  
Nuclear Reactions ◽  
Pauli Exclusion Principle ◽  
Significant Rise ◽  
Exclusion Principle ◽  
Reaction Products ◽  
Thermonuclear Reactions ◽  
Radiated Energy ◽  
Large Numbers ◽  
Stellar Interiors ◽  
Late Stages

Thermonuclear reactions provide the main source of radiated energy for stars and they are also believed to be responsible for the production of most of the heavy elements in the Universe. The thermonuclear plasma is confined by the force of gravitation and for most of a star’s history the reactions occur slowly and steadily. In some circumstances, the properties of a star change very rapidly and explosive nuclear reactions occur. In very dense stellar interiors the energy states available to electrons may be limited by the Pauli exclusion principle. When thermonuclear reactions start in such a degenerate gas, a rise in temperature is not accompanied by a significant rise in pressure and as a result there may be a runaway increase in reaction rate. In contrast, when reactions start in a non-degenerate gas, there is normally an effective thermostat. A star is usually opaque to reaction products, so that there is no problem in maintaining the reaction temperature, but at late stages of stellar evolution nuclear or elementary particle reactions may produce large numbers of neutrinos and antineutrinos that do escape.

scholarly journals THE RADIATED ENERGY BUDGET OF CHROMOSPHERIC PLASMA IN A MAJOR SOLAR FLARE DEDUCED FROM MULTI-WAVELENGTH OBSERVATIONS

2014 ◽  
Vol 793 (2) ◽  
pp. 70 ◽  
Author(s):  
Ryan O. Milligan ◽  
Graham S. Kerr ◽  
Brian R. Dennis ◽  
Hugh S. Hudson ◽  
Lyndsay Fletcher ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Budget ◽  
Radiated Energy ◽  
Multi Wavelength

scholarly journals Radiated energy and impurity density changes during intensive hydrogen influx in the PLT tokamak

1981 ◽  
Author(s):  
E. Hinnov ◽  
J. Hosea ◽  
H. Hsuan ◽  
F. Jobes ◽  
E. Meservey ◽  
...  
Keyword(s):  
Impurity Density ◽  
Radiated Energy
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