numerical simulations of silverpit crater collapse: a comparison of tekton and sales 2 gareth...
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![Page 1: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/1.jpg)
Numerical Simulations of Silverpit Crater Collapse:
A Comparison ofTEKTON and SALES 2
Gareth Collins, Zibi Turtle, and
Jay Melosh
LPL, Univ. of Arizona
![Page 2: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/2.jpg)
Silverpit(Stewart and Allen, 2002)
(Allen and Stewart, 2003)
![Page 3: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/3.jpg)
Objectives
• Understand Silverpit• Ring formation
• Compare 2 modeling techniques to assess:• Consistency• Limitations• Degree to which they are complementary
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Finite-Element Method• Model structure as an assemblage of elements
bounded by nodes• Specify:
• Geometry• Material properties and rheologies• Boundary and initial conditions
• Construct system of equations:• Solve simultaneously for displacements at nodes• Calculate stresses using constitutive equations
€
vf = K
v d
![Page 5: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/5.jpg)
Finite-element Method: Rheology• Elastic
• Newtonian
• Power-law
• Plastic• < c: power-law; ≥ c: Newtonian
• Exponential
€
ε =σE
€
˙ ε = Aσ n exp −H
RT
⎛ ⎝ ⎜
⎞ ⎠ ⎟
€
˙ ε = A' exp −H
RT1 −
σ
σ p
⎛
⎝ ⎜
⎞
⎠ ⎟
2 ⎛
⎝ ⎜ ⎜
⎞
⎠ ⎟ ⎟
€
˙ ε =σ
η
![Page 6: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/6.jpg)
Lagrangian Hydrocode Method• Model structure as a regular grid of cells
bounded by nodes• Specify:
• Geometry• Material properties• Boundary and initial conditions
• Calculate all forces acting on each cell.• Assuming forces constant for time step,
compute node displacements:
€
vx =
v f i∑
mΔt2
![Page 7: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/7.jpg)
Lagrangian Hydrocode: Rheology
• Elastic
• Newtonian fluid flow
• Plastic• < Y: elastic; ≥ Y: Newtonian• Yield strength Y may be a function of pressure,
pressure vibrations, damage and internal energy.
€
ε =σE
€
˙ ε =σ
η
![Page 8: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/8.jpg)
TEKTON (Finite-Element)
• Lagrangian
• Complex rheology
• Limited strength
• Faults
• No inertia
• Lagrangian
• Limited rheology
• Complex strength
• No faulting
• Inertia
SALES-2 (Hydrocode)
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TEKTON Silverpit Mesh
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TEKTON Silverpit Mesh
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TEKTON Silverpit Mesh
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TEKTON Silverpit Mesh
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TEKTON Silverpit Mesh
![Page 14: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/14.jpg)
TEKTON Silverpit Mesh
![Page 15: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/15.jpg)
TEKTON Silverpit Mesh
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SALES-2 Silverpit Mesh
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SALES-2 Silverpit Mesh
![Page 18: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/18.jpg)
SALES-2 Silverpit Mesh
![Page 19: Numerical Simulations of Silverpit Crater Collapse: A Comparison of TEKTON and SALES 2 Gareth Collins, Zibi Turtle, and Jay Melosh LPL, Univ. of Arizona](https://reader036.vdocuments.net/reader036/viewer/2022062321/56649ef15503460f94c022b6/html5/thumbnails/19.jpg)
SALES-2 Silverpit Mesh
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Results
• Central, near-surface, deformation differs• Comparable uplift at depth, few hundred m• Timescales for deformation differ• Magnitudes and orientations of surface
stresses outside of crater are consistent• Stress orientations and consequently fault
types are broadly consistent with Silverpit observations