anchor.diff:        PARAMETER (FMAX=1500)
         REAL*8 evlo(FMAX),evla(FMAX),evdp(FMAX),str(FMAX),dip(FMAX),
        1       rak(FMAX),dx(FMAX),dy(FMAX),slip(FMAX)
  -      REAL*8 uN,uE,uZ,strain(3,3),stress(3,3),norml,shear,coul
  +      REAL*8 uN,uE,uZ,strain(3,3),stress(3,3),norml,shear,coul,estrs
         REAL*8 az,hdsp
         INTEGER kffm,kflt,kmag,ksta,khaf,ktrg
         INTEGER kdsp,kstn,ksts,knor,kshr,kcou,kgmt
  
positive.code:               kstn = 1
                i = i + 1
                call getarg(i,stnf)
            elseif (tag(1:7).eq.'-stress') then
                if (kstn.eq.0) kstn = 2
                ksts = 1
  
negative.code:           write(*,*)
        endif
        write(*,*)
       1 '-estress STRSFILE       Effective stress (2nd invariant of ',
       2                                'dev. strs tensor)'
        if (str.eq.'long') then
            write(*,*)
            write(*,*)
       1 '    Format: stlo stla stdp estre(Pa)'
            write(*,*)
       1 '    The effective stress is a measure of the amplitude ',
       2       'of the stress tensor'
            write(*,*)
       1 '    (deviatoric part).'
            write(*,*)
       1 '        estre = 1/3*(s11*s11 + s22*s22 + s33*s33 -',
       2                      ' s11*s22 - s11*s33 - s22*s33)'
            write(*,*)
       1 '                          + (s12*s12 + s13*s13 + s23*s23)'
            write(*,*)
       1 '        estre = 1/6*((s11-s22)^2 + (s11-s33)^2',
       2                      ' + (s22-s33)^2)'
            write(*,*)
       1 '                          + (s12*s12 + s13*s13 + s23*s23)'
            write(*,*)
            write(*,9999)
            write(*,*)
        endif
        write(*,*)
       1 '-normal NORMFILE        Normal stress (',
       2                              'requires target fault kinematics)'
        if (str.eq.'long') then
  