Simple 2D locked fault model

globals[pos pos2 slp v r c]

turtles-own [x]

to setup
    ca ;; clear the world
    create-turtles 10;; make 10 new turtles
    [ask turtle 0 [set xcor 15 set ycor 0.5]
      ask turtle 2 [set xcor -15 set ycor 0.5]
      ask turtle 3 [set xcor 8 set ycor 0.5]
      ask turtle 4 [set xcor -8 set ycor 0.5]
     ask turtle 5 [set xcor 1.3 set ycor 0.5]
     ask turtle 1 [set xcor -1.3 set ycor 0.5]
    ask turtle 6 [set xcor 23 set ycor 0.5]
    ask turtle 7  [set xcor -23 set ycor 0.5]
    ask turtle 8  [set xcor 30 set ycor 0.5]
     ask turtle 9  [set xcor -30 set ycor 0.5]
    ]
    ask patches
    [set pcolor white
    ]
    ask patches with [pxcor = 0 and pycor > 1] [set pcolor brown]
    ask patches with [pxcor = 0 and pycor < 2] [set pcolor brown]
 reset-ticks
end 

to go
    move-turtles
    plot-v
    tick
end 

to move-turtles
  ask turtles [set x  xcor]

  ask turtles with [xcor > 1] [
    set heading 0
    set pos atan ((abs(xcor) ) / D) 1
     set pos2 atan ((abs(xcor) ) / D2)  1
     set slp pos - pos2
    forward slp * -0.00001 * S / pi
  ]
   ask turtles with [xcor < 1] [
   set heading 180
    set pos atan ((abs(xcor) ) / D) 1
     set pos2 atan ((abs(xcor) ) / D2)  1
     set slp pos - pos2
    forward slp * -0.00001 * S / pi
  ]
end 

to plot-v
    set r r + 0.01
    set c 0.0185
    set v (- S * c / 3.14) * (atan ( r / D) 1 - atan ( r / D2) 1)
    plotxy r v
end