Fsa: data

Data

Internal Representation

• Fault data
  • The basic fault data type is represented by 4 numbers:
    • 3 real numbers: strike, dip and rake (α, δ, λ) defined as in (Aki & Richard, 1980, page 106)
    • 1 integer number: the fault identification number, either read in the input file or generated, depending on formats.
  • Other fault data type are derived from the basic data type
    • either by including additional information such as
      • bedding orientation (to correct for tilting)
      • location given by 1 or 3 coordinates
      • second nodal plane of fault plane solutions
      • rake range when slip is only constrained to belong to a sector
    • or by restricting information such as
      • no slip information: fault plane only
• Stress data
  • The basic stress data type is represented by 5 numbers:
    • 3 real numbers: the Euler's angles θ, φ and ψ, that define the orientation of the principal stress direction in the geographical frame. These angles are defined as in (Celerier,1988, Fig 2) after replacing e₁, e₂, e₃ by North, East and Down.
    • 1 real number: the stress tensor aspect ratio defined as in (Celerier,1988; Celerier,1995) :
      r₀ = (σ₁ - σ₂)/(σ₁ - σ₃) where σ₁ ≥ σ₂ ≥ σ₃
      
    • 1 integer number: the stress data identification number, either read in the input file or generated, depending on formats.
  • Other stress data type are derived from the basic data type
    • by including additional information such as
      • projection of principal stress directions into the horizontal plane (for mapping)
      • location given by 2 or 3 coordinates

Input and Output Files

Input can be either fault or stress data. Output can also be either fault or stress data. That means one can invert stress from fault data (input = fault, output = stress), generate fault compatible with a stress state (input = stress, output = fault), or analyse the relationship between fault and stress (input = stress AND fault).

The various types and formats of input fault and stress data files are detailed in the user's manual.

Note that conversion between formats can be achieved by reading data from an input file in one format and writing them into an output file in a different format.

References

• Aki, K. and Richards, P., 1980. Quantitative seismology, theory and methods, Freeman, Vol I, 557p.
  
  
• Célérier, B.,  1988, How much does slip on a reactivated fault plane constrain the stress tensor ? , Tectonics, 7, 1257-1278, doi:10.1029/TC007i006p01257.
  
  
• Célérier, B., 1995, Tectonic regime and slip orientation of reactivated faults, Geophysical Journal International, 121, 143-191, doi:10.1111/j.1365-246X.1995.tb03517.x, and Erratum, Geophysical Journal International, 122, 703, doi:10.1111/j.1365-246X.1995.tb07021.x.