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Nonlinear, Nonequilibrium Elasticity in Diverse Materials

Featured Article

Cascading Elastic Perturbation in Japan Due to the
2012 Mw 8.6 Indian Ocean Earthquake

Since the discovery of extensive earthquake triggering occurring in response to the 1992 Mw (moment magnitude) 7.3 Landers earthquake, it is now well established that seismic waves from earthquakes can trigger other earthquakes, tremor, slow slip, and pore pressure changes. Our contention is that earthquake triggering is one manifestation of a more widespread elastic disturbance that reveals information about Earth's stress state. Earth's stress state is central to our understanding of both natural and anthropogenic-induced crustal processes.

We show that seismic waves from distant earthquakes may perturb stresses and frictional properties on faults and elastic moduli of the crust in cascading fashion. Transient dynamic stresses place crustal material into a metastable state during which the material recovers through a process termed slow dynamics. This observation of widespread, dynamically induced elastic perturbation, including systematic migration of offshore seismicity, strain transients, and velocity transients, presents a new characterization of Earth's elastic system that will advance our understanding of plate tectonics, seismicity, and seismic hazards.

A. A. Delorey, K. Chao, K. Obara, P. A. Johnson, Cascading elastic perturbation in Japan due to the 2012 Mw 8.6 Indian Ocean earthquake. Sci. Adv. 1, e1500468 (2015) doi: 10.1126/sciadv.1500468. (PDF File - 1.6 MB)



Dynamic nonlinear elastic behavior, nonequilibrium dynamics, first observed as a curiosity in earth materials has now been observed in a great variety of solids. The primary manifestations of the behavior are characteristic wave distortion, and slow dynamics, a recovery process to equilibrium that takes place linearly with the logarithm of time, over hours to days after a wave disturbance. The link between the diverse materials that exhibit nonequilibrium dynamics appears to be the presence of soft regions, thought to be primarily 'damage' at many scales, ranging from order 10-9 m to 10-1 m at least. The regions of soft matter may be distributed as in a rock sample, or isolated, as in a sample with a single crack. The precise physical origin of the behavior is clear in some cases such as granular media where the source of the nonequilibrium dynamics, grain-to-grain interaction, is well understood. In other materials, it appears that the origin must be due fundamentally to shear sliding, related to crack and possibly dislocation dynamics, as well as less clear origins. Because the physical origins of the behavior are related to damage, damage diagnostics in solids, Nonlinear NonDestructive Evaluation, follows naturally. Nonequilibrium dynamics also plays a significant role in other areas such as earthquake strong ground motion and potentially to earthquake dynamics.

For more information, please contact Paul Johnson.

Book Published - Nonlinear Mesoscopic Elasticity

Authors Robert A. Guyer and Paul A. Johnson have published Nonlinear Mescopic Elasticity. This book is available from both Amazon and the publisher, Wiley VCH. (Sample Chapter)

  • Print ISBN: 9783527407033
  • Online ISBN: 9783527628261
  • DOI: 10.1002/9783527628261
  • Copyright © 2009 Wiley-VCH Verlag GmbH & Co. KGaA

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