Spatial Distribution of Viscoelastic Relaxation Following a Subduction Earthquake

Mapping Intimacies ◽

10.5194/egusphere-egu2020-6756 ◽

2020 ◽

Author(s):

Yuting Ji ◽

Wenke Sun ◽

He Tang

Keyword(s):

Spatial Distribution ◽

Relaxation Time ◽

Sea Water ◽

Characteristic Relaxation Time ◽

Viscoelastic Relaxation ◽

Gravity Field Model ◽

Viscoelastic Characteristic ◽

Gravity Changes ◽

2004 Sumatra Earthquake ◽

Seismic Deformation

<p>Viscoelastic relaxation is generally considered as the dominant process of the long-term post-seismic deformation, while viscoelastic characteristic relaxation time represents the time scale of deformation caused by viscoelastic relaxation effect after the earthquake. The subduction earthquakes which occurred at the boundary of the ocean and continental plates often release greater stress, and the stress relaxation of mantle materials is more significant due to the response to viscoelasticity. Satellite gravity mission GRACE (gravity recovery and climate experience) is able to observe the corresponding co-seismic and post-seismic gravity changes. Therefore, in this study, we use the monthly gravity field model data of GRACE RL06 to study the post-seismic gravity changes of 2011 Tohoku earthquake and 2004 Sumatra earthquake. After removing the influence of sea level changes, GIA changes and GLDAS on the seasonal precipitation changes in the land area, as well as the sea water correction, we get the post-seismic deformation only related to the deformation of the solid earth. Then we use the attenuation function to fit each grid value and obtain the spatial distribution of viscoelastic characteristic relaxation time after rejecting the afterslip from the total post-seismic deformation. Thus&#65292;we can capture &#160;the viscous structure in the subduction area.</p>

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Cooperative Domain Model for Yield Phenomenon

MRS Proceedings ◽

10.1557/proc-215-71 ◽

1990 ◽

Vol 215 ◽

Author(s):

S. Matsuoka

Keyword(s):

Relaxation Time ◽

Strain Rate ◽

Yield Stress ◽

Molecular Model ◽

Configurational Entropy ◽

Domain Model ◽

Characteristic Relaxation Time ◽

Viscoelastic Relaxation ◽

Classical Plasticity ◽

Linear Viscoelastic

AbstractA molecular model for cooperative segmental relaxation has been proposed, which leads to the Adam-Gibbs type dependence of the characteristic relaxation time on temperature and the configurational entropy. When the size distribution for the cooperative domains is introduced, the resulting relaxation spectrum is similar to the Kohlrausch-Williams-Watts (KWW) equation in the frequency range near the loss maximum, but the fit is actually better in the high frequency extremes where the KWW equation always underpredicts the intensity. The model also predicts the broad spread of the spectrum in the non-equilibrium state from the distribution of the apparent activation energy arising from the different sizes of domains.We now extend this model to the yield phenomenon in glassy polymers. Under the stress, a domain has two alternatives to dissipate the strain energy. One way is to relieve the stress at the rate dictated by the linear viscoelastic relaxation time. This process is possible only when the strain rate is low. At above a certain strain rate, the stress reaches the strength of the domain, forcing to irreversibly break up the domain structure in the manner that can be described by the classical plasticity. It can be shown that the yield stress of a real polymer is a combination of the above two types of stresses. Namely, at a given strain rate, the small domains with short relaxation time will attain the linear viscoelastic steady stress while the larger domains reach the (limiting) plastic yield stress. Thus, the strain rate dependence of yield stress can be predicted from the linear viscoelastic relaxation spectra, even though the yield phenomenon is clearly in the realm of nonlinear viscoelasticity.

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Induced polarization and pore radius — A discussion

Geophysics ◽

10.1190/geo2016-0135.1 ◽

2016 ◽

Vol 81 (5) ◽

pp. D519-D526 ◽

Cited By ~ 13

Author(s):

Andreas Weller ◽

Zeyu Zhang ◽

Lee Slater ◽

Sabine Kruschwitz ◽

Matthias Halisch

Keyword(s):

Diffusion Coefficient ◽

Relaxation Time ◽

Diffusion Coefficients ◽

Pore Radius ◽

Mercury Porosimetry ◽

Induced Polarization ◽

Reliable Estimate ◽

Characteristic Relaxation Time ◽

A Value ◽

Apparent Diffusion

Permeability estimation from induced polarization (IP) measurements is based on a fundamental premise that the characteristic relaxation time [Formula: see text] is related to the effective hydraulic radius [Formula: see text] controlling fluid flow. The approach requires a reliable estimate of the diffusion coefficient of the ions in the electrical double layer. Others have assumed a value for the diffusion coefficient, or postulated different values for clay versus clay-free rocks. We have examined the link between a widely used single estimate of [Formula: see text] and [Formula: see text] for an extensive database of sandstone samples, in which mercury porosimetry data confirm that [Formula: see text] is reliably determined from a modification of the Hagen-Poiseuille equation assuming that the electrical tortuosity is equal to the hydraulic tortuosity. Our database does not support the existence of one or two distinct representative diffusion coefficients but instead demonstrates strong evidence for six orders of magnitude of variation in an apparent diffusion coefficient that is well-correlated with [Formula: see text] and the specific surface area per unit pore volume [Formula: see text]. Two scenarios can explain our findings: (1) the length scale defined by [Formula: see text] is not equal to [Formula: see text] and is likely much longer due to the control of pore-surface roughness or (2) the range of diffusion coefficients is large and likely determined by the relative proportions of the different minerals (e.g., silica and clays) making up the rock. In either case, the estimation of [Formula: see text] (and hence permeability) is inherently uncertain from a single characteristic IP relaxation time as considered in this study.

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Multiscale Post-Seismic Deformation Based on cGNSS Time Series Following the 2015 Lefkas (W. Greece) Mw6.5 Earthquake

Applied Sciences ◽

10.3390/app11114817 ◽

2021 ◽

Vol 11 (11) ◽

pp. 4817

Author(s):

Filippos Vallianatos ◽

Vassilis Sakkas

Keyword(s):

Time Series ◽

Relaxation Time ◽

Relaxation Times ◽

Relaxation Mechanism ◽

Mesoscopic Scale ◽

Macroscopic Scale ◽

Epicentral Area ◽

Arrhenius Dependence ◽

Seismic Deformation ◽

Logarithmic Type

In the present work, a multiscale post-seismic relaxation mechanism, based on the existence of a distribution in relaxation time, is presented. Assuming an Arrhenius dependence of the relaxation time with uniform distributed activation energy in a mesoscopic scale, a generic logarithmic-type relaxation in a macroscopic scale results. The model was applied in the case of the strong 2015 Lefkas Mw6.5 (W. Greece) earthquake, where continuous GNSS (cGNSS) time series were recorded in a station located in the near vicinity of the epicentral area. The application of the present approach to the Lefkas event fits the observed displacements implied by a distribution of relaxation times in the range τmin ≈3.5 days to τmax ≈350 days.

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Primitive chain network simulations of probe rheology

Soft Matter ◽

10.1039/c7sm01229b ◽

2017 ◽

Vol 13 (37) ◽

pp. 6585-6593 ◽

Cited By ~ 6

Author(s):

Yuichi Masubuchi ◽

Yoshifumi Amamoto ◽

Ankita Pandey ◽

Cheng-Yang Liu

Keyword(s):

Relaxation Time ◽

Viscoelastic Relaxation ◽

Network Simulations ◽

Cross Correlations

The dynamics of probe chains immersed in immobile matrices was examined via the multi-chain slip-link simulation. The viscoelastic relaxation time was fairly reproduced, whereas the relaxation intensity was underestimated, possibly due to flaws in the orientational cross-correlations between the probe and the matrices.

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A Distinguishable Role of eDNA in the Viscoelastic Relaxation of Biofilms

mBio ◽

10.1128/mbio.00497-13 ◽

2013 ◽

Vol 4 (5) ◽

Cited By ~ 45

Author(s):

Brandon W. Peterson ◽

Henny C. van der Mei ◽

Jelmer Sjollema ◽

Henk J. Busscher ◽

Prashant K. Sharma

Keyword(s):

Relaxation Time ◽

Stress Relaxation ◽

Time Constant ◽

Extracellular Polymeric Substances ◽

Principal Component ◽

Mechanical Stresses ◽

Extracellular Dna ◽

Viscoelastic Relaxation ◽

Content Type ◽

Relaxation Time Constants

ABSTRACTBacteria in the biofilm mode of growth are protected against chemical and mechanical stresses. Biofilms are composed, for the most part, of extracellular polymeric substances (EPSs). The extracellular matrix is composed of different chemical constituents, such as proteins, polysaccharides, and extracellular DNA (eDNA). Here we aimed to identify the roles of different matrix constituents in the viscoelastic response of biofilms.Staphylococcus aureus,Staphylococcus epidermidis,Streptococcus mutans, andPseudomonas aeruginosabiofilms were grown under different conditions yielding distinct matrix chemistries. Next, biofilms were subjected to mechanical deformation and stress relaxation was monitored over time. A Maxwell model possessing an average of four elements for an individual biofilm was used to fit the data. Maxwell elements were defined by a relaxation time constant and their relative importance. Relaxation time constants varied widely over the 104 biofilms included and were divided into seven ranges (<1, 1 to 5, 5 to 10, 10 to 50, 50 to 100, 100 to 500, and >500 s). Principal-component analysis was carried out to eliminate related time constant ranges, yielding three principal components that could be related to the known matrix chemistries. The fastest relaxation component (<3 s) was due to the presence of water and soluble polysaccharides, combined with the absence of bacteria, i.e., the heaviest masses in a biofilm. An intermediate component (3 to 70 s) was related to other EPSs, while a distinguishable role was assigned to intact eDNA, which possesses a unique principal component with a time constant range (10 to 25 s) between those of EPS constituents. This implies that eDNA modulates its interaction with other matrix constituents to control its contribution to viscoelastic relaxation under mechanical stress.IMPORTANCEThe protection offered by biofilms to organisms that inhabit it against chemical and mechanical stresses is due in part to its matrix of extracellular polymeric substances (EPSs) in which biofilm organisms embed themselves. Mechanical stresses lead to deformation and possible detachment of biofilm organisms, and hence, rearrangement processes occur in a biofilm to relieve it from these stresses. Maxwell analysis of stress relaxation allows the determination of characteristic relaxation time constants, but the biofilm components and matrix constituents associated with different stress relaxation processes have never been identified. Here we grew biofilms with different matrix constituents and used principal-component analysis to reveal that the presence of water and soluble polysaccharides, together with the absence of bacteria, is associated with the fastest relaxation, while other EPSs control a second, slower relaxation. Extracellular DNA, as a matrix constituent, had a distinguishable role with its own unique principal component in stress relaxation with a time constant range between those of other EPSs.

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A Viscoelastic Relaxation Model for Post-Seismic Deformation from the San Francisco Earthquake of 1906

Stress in the Earth ◽

10.1007/978-3-0348-5745-1_25 ◽

1977 ◽

pp. 401-411 ◽

Cited By ~ 1

Author(s):

John B. Rundle ◽

David D. Jackson

Keyword(s):

San Francisco ◽

Viscoelastic Relaxation ◽

Relaxation Model ◽

Seismic Deformation

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Thermodynamic Analysis of Relaxation Model for Non-Equilibrium Phase Behavior of Hydrocarbon Mixtures

Journal of Physics Conference Series ◽

10.1088/1742-6596/2090/1/012138 ◽

2021 ◽

Vol 2090 (1) ◽

pp. 012138

Author(s):

I M Indrupskiy ◽

P A Chageeva

Keyword(s):

Relaxation Time ◽

Phase Behavior ◽

Relaxation Process ◽

Thermodynamic Analysis ◽

Balance Equation ◽

Equilibrium Phase ◽

Characteristic Relaxation Time ◽

Relaxation Model ◽

Entropy Balance ◽

Non Equilibrium

Abstract Mathematical models of phase behavior are widely used to describe multiphase oil and gas-condensate systems during hydrocarbon recovery from natural petroleum reservoirs. Previously a non-equilibrium phase behavior model was proposed as an extension over generally adopted equilibrium models. It is based on relaxation of component chemical potentials difference between phases and provides accurate calculations in some typical situations when non-instantaneous changing of phase fractions and compositions in response to variations of pressure or total composition is to be considered. In this paper we present a thermodynamic analysis of the relaxation model. General equations of non-equilibrium thermodynamics for multiphase flows in porous media are considered, and reduced entropy balance equation for the relaxation process is obtained. Isotropic relaxation process is simulated for a real multicomponent hydrocarbon system with different values of characteristic relaxation time using the non-equilibrium model implemented in the PVT Designer module of the RFD tNavigator simulation software. The results are processed with a special algorithm implemented in Matlab to calculate graphs of the total entropy time derivative and its constituents in the entropy balance equation. It is shown that the constituents have different signs, and the greatest influence on the entropy is associated with the interphase flow of the major component of the mixture and the change of the total system volume in the isotropic process. The characteristic relaxation time affects the rate at which the entropy is approaching its maximum value.

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Studies on dielectric relaxation in relation to viscosity of some anilines, phenol, and their binary mixtures at microwave frequencies

Canadian Journal of Physics ◽

10.1139/cjp-2018-0136 ◽

2019 ◽

Vol 97 (2) ◽

pp. 210-215

Author(s):

C.V. Maridevarmath ◽

G.H. Malimath

Keyword(s):

Relaxation Time ◽

Steady State ◽

Dynamic Viscosity ◽

Room Temperature ◽

Viscoelastic Model ◽

Frictional Resistance ◽

Nonlinear Behaviour ◽

Viscoelastic Relaxation ◽

Microwave Frequencies ◽

Loss Formula

In the present work, the study of variation of relaxation time (τ) with viscosity of the medium (η) is carried out on four polar samples: 2-Nitroaniline, 4-Bromoaniline, 4-Chloroaniline, 4-Chlorophenol, and also on the binary mixture of 2-Nitroaniline + 4-Bromoaniline at room temperature by using microwave bench operating at a frequency of 9.59 GHz. In this regard, the different parameters like dielectric constant ([Formula: see text]), dielectric loss ([Formula: see text]), relaxation time (τs), macroscopic steady state viscosity (ηs), dynamic viscosity (ηd), and viscoelastic relaxation time (τve) were determined for all the systems. It is observed that the relaxation time (τs) increases with the increase in the viscosity of the medium for all the systems. Plots of log(τs) versus log(ηs) for all the systems show that variation of relaxation time is found to be nonlinear in the higher viscosity regions. This suggests the failure of Debye’s theory at these regions. Further, the nonlinear behaviour of relaxation time with the viscosity is explained by using the viscoelastic model suggested by Barlow et al. (Proc. R. Soc. A 309, 473 (1969). doi: 10.1098/rspa.1969.0053 ). It is also observed that macroscopic steady state viscosity (ηs) values are greater than the dynamic viscosity (ηd), and viscoelastic relaxation time (τve) values were found to be lower compared to the relaxation time (τs). These results suggest that the effective frictional resistance experienced by the molecules during reorientation is lower and the measured values of macroscopic steady state viscosity (ηs) are frequency dependent.

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