Spatiotemporal Properties of Sub‐Rayleigh and Supershear Ruptures Inferred From Full‐Field Dynamic Imaging of Laboratory Experiments

Rubino, V.; Rosakis, Ares J.; Lapusta, N.

doi:10.1029/2019jb018922

Cited by 24 publications

(27 citation statements)

References 67 publications

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“…First, they were conducted using specimens of PMMA. Second, they used a new, ultra-fast, diagnostic technique [40,41,33] capable of recording full-field maps of all components of displacement, strain, and strain rate near the propagating rupture in real time. This method, called dynamic digital image correlation (DIC), has been used in conjunction with ultra-high-speed photography to accurately visualize strain discontinuities (such as those associated with Mach lines), more accurately than ever before [33].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Flexoelectric Materials: Subsonic, Intersonic, and Supersonic Ruptures and Mach Cone Formation

Giannakopoulos

Rosakis

2020

Journal of Applied Mechanics

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Motivated by recent, unexpected, experimental observations of “intersonic” rupture growth in which both shear and dilatational Mach fronts were observed at the tips of dynamic frictional ruptures propagating at rupture speeds below the dilatational wave speed of the surrounding solid, and we formulate the general dynamic flexoelectric problem and we investigate its plane strain/plane polarization specialization. The coupling of the mechanical problem is analogous to a problem of Toupin–Mindlin gradient elasticity, where two micromechanical characteristic lengths and two microinertial lengths emerge as a combination of the mechanical, dielectric, and flexoelectric constants. The solution of the rupture growth problem allows us to provide an explanation of the experimental results. This becomes possible since flexoelectricity predicts a new aspect that was not observed in the classical analysis: subsonic super shear and supersonic crack tip (or rupture) motions are not related exclusively with the problem being elliptic or hyperbolic, respectively. This is due to the influence of the microinertial lengths, which, in addition to the ratios of the rupture to the wave speeds, also affect the slopes of the Mach cones. Moreover, we are able to explain the experimental paradox of the observation of double Mach cone pairs at the tips of supershear, but subsonic, frictional, ruptures in poly-methyl-methacrtylate (PMMA) by demonstrating that both dilatational and shear Mach cones could appear in flexoelectric solids at rupture speeds below the material dilatation wave speed, something that is impossible from the classical elasticity analysis and is due to the dispersive nature of the present problem. Our analysis is of relevance to the dynamic deformation and fracture of both synthetic and naturally occurring flexoelectric materials and systems, with implications to both engineering and earthquake source mechanics.

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Section: Introductionmentioning

confidence: 99%

Dynamics of Flexoelectric Materials: Subsonic, Intersonic, and Supersonic Ruptures and Mach Cone Formation

Giannakopoulos

Rosakis

2020

Journal of Applied Mechanics

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“…These in-plane components of these ruptures are discussed in Ref. [153]. Note that the supershear rupture of Figs.…”

Section: Imaging the Formation Of Pressure Shock Frontsmentioning

confidence: 80%

“…13( f )). Both are of the same order of magnitude as their fault-parallel velocity components [153]. To summarize, this analysis indicates that (i) the out-of-plane velocities are more important than the out-of-plane displacements when compared with the respective in-plane components and (ii) the out-of-plane velocities are much more important for strong supershear ruptures V r > 2 √ c HSR s than they are for sub-Rayleigh or supershear ruptures propagating at the Eshelby speed, which has important implications for ground motion scenarios associated with these types of earthquakes.…”

Section: Imaging the Formation Of Pressure Shock Frontsmentioning

confidence: 94%

“…The maximum values of the out-of-plane displacements are smaller when compared with the in-plane components. For example, the sub-Raleigh rupture has maximum in-plane displacements on the order of 15 µm [153], while the estimated out-of-plane component is on the order of 2 µm. For the case of the supershear rupture propagating at V r > 2 √ c HSR s , the fault-parallel displacement component is on the order of 50 µm at a time t = 37.6 µs after rupture nucleation, and it occurs behind the rupture tip where slip accumulates.…”

Section: Imaging the Formation Of Pressure Shock Frontsmentioning

confidence: 99%

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Recent Milestones in Unraveling the Full-Field Structure of Dynamic Shear Cracks and Fault Ruptures in Real-Time: From Photoelasticity to Ultrahigh-Speed Digital Image Correlation

Rosakis

Rubino

Lapusta

2020

Journal of Applied Mechanics

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The last few decades have seen great achievements in dynamic fracture mechanics. Yet, it was not possible to experimentally quantify the full-field behavior of dynamic fractures, until very recently. Here, we review our recent work on the full-field quantification of the temporal evolution of dynamic shear ruptures. Our newly developed approach based on digital image correlation combined with ultrahigh-speed photography has revolutionized the capabilities of measuring highly transient phenomena and enabled addressing key questions of rupture dynamics. Recent milestones include the visualization of the complete displacement, particle velocity, strain, stress and strain rate fields near growing ruptures, capturing the evolution of dynamic friction during individual rupture growth, and the detailed study of rupture speed limits. For example, dynamic friction has been the biggest unknown controlling how frictional ruptures develop but it has been impossible, until now, to measure dynamic friction during spontaneous rupture propagation and to understand its dependence on other quantities. Our recent measurements allow, by simultaneously tracking tractions and sliding speeds on the rupturing interface, to disentangle its complex dependence on the slip, slip velocity, and on their history. In another application, we have uncovered new phenomena that could not be detected with previous methods, such as the formation of pressure shock fronts associated with “supersonic” propagation of shear ruptures in viscoelastic materials where the wave speeds are shown to depend strongly on the strain rate.

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“…While strike slip faults generate pre-dominantly horizontal displacements, there still is a non-negligible vertical component that emerges at the seafloor to satisfy the plane stress condition at the free surface. This is true especially when these ruptures are supershear in which case, this out of plane displacement is not localized at the rupture tip but extends along the Mach fronts (43,50). Simultaneously, gravity driven tsunami waves start to evolve over the banks of the bay.…”

mentioning

confidence: 99%

Anatomy of Strike Slip Fault Tsunami-genesis

Elbanna¹,

Abdelmeguid²,

Ma³

et al. 2023

Preprint

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Tsunami generation from earthquake induced seafloor deformations has long been recognized as a major hazard to coastal areas. Strike-slip faulting has generally been believed as insufficient for triggering large tsunamis, except through the generation of submarine landslides. Herein, we demonstrate that ground motions due to strike-slip earthquakes can contribute to the emergence of large tsunamis (>1m) under rather generic conditions. To this end, we have developed a computational framework that integrates models for earthquake rupture dynamics with models of tsunami generation and propagation. The three-dimensional time-dependent vertical and horizontal ground motions from spontaneous dynamic rupture models are used to drive boundary motions in the tsunami model. Our results suggest that supershear ruptures propagating along strike-slip faults, traversing narrow and shallow bays are prime candidates for tsunami generation. We show that dynamic focusing and the large horizontal displacements, characteristic of strike-slip earthquakes on long faults, are critical drivers for the tsunami hazard. These findings point to intrinsic mechanisms for sizeable tsunami generation by strike-slip faulting, which do not require complex seismic sources, landslides, or complicated bathymetry. Furthermore, our model identifies three distinct phases in the tsunamic motion; an instantaneous dynamic phase, a lagging coseismic and a classical postseismic phase, each of which may affect coastal areas differently. We conclude that near-source tsunami hazards and risk from strike-slip faulting need to be re-evaluated.

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Spatiotemporal Properties of Sub‐Rayleigh and Supershear Ruptures Inferred From Full‐Field Dynamic Imaging of Laboratory Experiments

Cited by 24 publications

References 67 publications

Dynamics of Flexoelectric Materials: Subsonic, Intersonic, and Supersonic Ruptures and Mach Cone Formation

Dynamics of Flexoelectric Materials: Subsonic, Intersonic, and Supersonic Ruptures and Mach Cone Formation

Recent Milestones in Unraveling the Full-Field Structure of Dynamic Shear Cracks and Fault Ruptures in Real-Time: From Photoelasticity to Ultrahigh-Speed Digital Image Correlation

Anatomy of Strike Slip Fault Tsunami-genesis

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