These are an explanation for grflt94.in, which is the input data file for the grflt94.f.


In grflt94.in

     1    1    1  : Number of Sub-Faults (NSTR,NDIP),Gauss Points (1-6)

NSTR and NDIP are the numbers of sub-faults along the strike and dip directions, respectively. Gauss Point is a number of integration points (source points) on each sub-faults using Gaussain Quadrature. I used this to express smooth and continuous rupture front. For example, when you subdivide the fault into 6 by 6 using 4 Gaussian points, the data should be

     6    6    4  : Number of Sub-Faults (NSTR,NDIP),Gauss Points (1-6)

Note that the Gaussian points are along both strike and dip directions,namely, 4 x 4 = 16 points on each sub-faults.Therefore the total number of source points on the fault plane is 6 x 6 x 4 x 4 = 576 points.

        1     0.0 : Number of Time Windows and Time Interval (sec)
      0.2     0.2 : Half-Rise time 1 & 2 for 1st Time Window (sec)

Time Window is actually a slip velocity (source time) function. For the above example, the slip velocity function is a single equilateral triangle and its duration is 0.4 (0.2+0.2) second. We can extend it for more complicated source time functions by superposing triangles. For example, when you use a source time function of 3 triangles with 0.4, 0.5, and 0.6 d0urations, and the intervals of the triangles 0.3 second, the data should be

        3     0.3 : Number of Time Windows and Time Interval (sec)
      0.2     0.2 : Half-Rise time 1 & 2 for 1st Time Window (sec)
     0.25    0.25 : Half-Rise time 1 & 2 for 1st Time Window (sec)
      0.3     0.3 : Half-Rise time 1 & 2 for 1st Time Window (sec)

In this program, you can use multiple triangles up to 6.


* dislocations (m) on sub-faults up to 6 time windows
     1.2

  * rake angles (degree) on sub-faults for 6 time windows
     57.0

Suppose you subdivide the fault into 4 x 3 sub-faults for the strike and dip directions, and you have the following slip distribution (unit: m),

1.2 2.1 1.2 0.6
2.1 1.2 1.5 2.1
0.9 0.6 1.5 1.5

The data for the dislocations should be

* dislocations (m) on sub-faults up to 6 time windows
0.9
0.6
1.5
1.5
2.1
1.2
1.5
2.1
1.2
2.1
1.2
0.6

This is for the source time function with a single triangle. When you use multiple triangles, you have to divide the slip into sub-slips according to the corresponding area (slip) of triangles. For example, when you subdivide the above slips into 3 triangles with the same slip, the data should be

* dislocations (m) on sub-faults up to 6 time windows
0.3 0.3 0.3
0.2 0.2 0.2
0.5 0.5 0.5
0.5 0.5 0.5
0.7 0.7 0.7
0.4 0.4 0.4
0.5 0.5 0.5
0.7 0.7 0.7
0.4 0.4 0.4
0.7 0.7 0.7
0.4 0.4 0.4
0.2 0.2 0.2

The data for the rake angles are the same. Same as the above data, when you have 4 x 3 subfaults with the source time function of three triangles, and suppose the all rake angles are same, 25 degree, the data should be

* rake angles (degree) on sub-faults for 6 time windows
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0
25.0 25.0 25.0

Yoshiaki Hisada

