Dear all,

I want to calculate the Coulomb stress (CFS) through the Traction_change on one fault in Pylith.

I checked the fault_info file (strike_dir,dip_dir, normal_dir), but it doesn’t seem to be consistent with the results of the direction value that I calculated according to my formula ( δ,dip angle; φ, strike angle; λ， slip angle; 1. normal_dir: x= sinδ×cosφ, y= -sinδ×sinφ， z= cosδ ; 2. strike_dir: x= sinφ, y= cosφ, z=0; 3. dip_dir: x= cosφ×cosδ, y= -sinφ×cosδ, z= sinδ)

In addition, if Traction_change_Z (TZ) on the fault is in the direction of fault opening, it should be projected on the normal and slip direction of the fault, and the CFS can be calculated by the formula : CFS = TX×cosλ + (TY+TZ×cosδ)×sinλ - μ×TZ×sinδ ？ The result seems not be correct.

Thank you in advance.

Best regards

Peiyu