SCEC TPV12

TPV12 and 13 are recommended by SCEC for elastic/plastic wave propagation code validation. TPV 12 describes spontaneous rupture on a 60-degree dipping normal fault in a homogeneous half-space. Material properties are linear elastic. Initial stress conditions are dependent on depth. Strongly super-shear rupture conditions.

Diagram of geometry of TPV12/13.

Diagram of the geometry of TPV12/13. 60-degree dipping normal fault.

Geometry

The model volume is a half-space. The fault is a 60-degree dipping, planar, normal fault. The fault reaches the Earth’s surface. Rupture is allowed within a rectangular area measuring 30000 m along-strike and 15000 m down-dip.

Note that 15000 m down-dip corresponds to a depth of 12990.38 m. A node which lies exactly on the border of the 30000 m \(\times\) 15000 m rectangle is considered to be inside the rectangle, and so should be permitted to rupture.

The portions of the fault below, to the left of, and to the right of the 30000 m \(\times\) 15000 m rectangle are a strength barrier, within which the fault is not allowed to rupture.

The nucleation zone is a square measuring 3000 m × 3000 m. The center of the square is located 12000 m down-dip (at a depth of 10392.30 m), and is centered along-strike.

The geometry is generated with GMSH. All the files that are needed for the simulation are provided in

Diagram of a 60-degree dipping fault in Gmsh.

Diagram of a 60-degree dipping fault in Gmsh. The surrouding box is 500 km long and 500 km wide and 50 km high. The fault cuts through the free surface.

The geometry and mesh generation process is similar to TPV5. The planar-fault geometry is built with Gmsh (Figure [fig:tpv12geo]). All the files that are needed for the simulation are provided in .

Nucleation

In previous benchmarks, nucleation was achieved by imposing a higher initial shear stress within a nucleation zone. In TPV12 and TPV13, nucleation is achieved by selecting a lower static coefficient of friction within a nucleation zone, so that the initial shear stress (which is implied by the initial stress tensor) is greater than the yield stress.

Outside the 30000 m * 15000 m rectangular rupture area there is a strength barrier, where nodes are not allowed to slip. Some codes implement the strength barrier by setting the static coefficient of friction and frictional cohesion to very large values. Other codes implement the strength barrier in other ways.

Parameters

LSR parameters

TPV12 uses a linear slip weakening law on the fault with different parameters inside and outside the nucleation zone. The parameters are listed in Table [table:tpv12lsr].

Parameter inside the nucleation zone Value Unit
inside the nucleation zone
mu_s static friction coefficient 0.54  
mu_d dynamic friction coefficient 0.10  
d_c critical distance 0.50 m
cohesion shear stress cohesion -200 000 Pa
outside the nucleation zone
mu_s static friction coefficient 0.70  
mu_d dynamic friction coefficient 0.10  
d_c critical distance 0.50 m
cohesion shear stress cohesion -200 000 Pa

Table: Table of LSR parameters on the fault.

Initial stress

The initial stress on the fault is depth-dependent in TPV12/13. In the shallower portion above 11951.15 m, the stress field is optimal orientated while the other is isotropic.

Parameter Value
above 11951.15 m
\(\sigma_1\) 26460 Pa/m * H
\(\sigma_3\) 15624.3 Pa/m * H
\(\sigma_2\) \((\sigma_1+\sigma_3)/2\)
\(P_f\) \(1000 kg/m^3 *9.8 m/s^2 *H\)
below 11951.15 m
\(\sigma_1,\sigma_2,\sigma_3\) \(2700 kg/m^3 *9.8 m/s^2 *H\)

Results

SeisSol output xdmf file that can be loaded in Paraview directly. The wave field and fault output files have the same format as in TPV5.

Paraivew figure of TPV12 output.

Paraivew figure of TPV12 output. Fault slip rate in dip-direction (SRd) and vertical velocity (w) in wave field. The roughed cutoff surface demonstrates the unstructured tetrahedral meshing.