So, this "hatchet throwing" business.... how far past the target is necessary for a safety zone? Is there a standard size for a "missed hatchet landing area" or something? 
Who said anything about a hatchet? We're talking axes!
JK, This needs to be modified for whatever we have. Here's some basic rules in the attachment.
https://www.baileysonline.com/PDF/axe_throwing_lumberjack_rules.pdfAxe Throwing
1. Center of bull’s eye is to be exactly 60 inches from the ground. The target will be
36 inches in diameter with five scoring areas; 4 inch bull’s eye with 4 inch width
rings. The bull’s eye shall score 5 points, the next outside area 4 points, the next
outer 3 points, next 2 points and the next 1 point. If hole is drilled into center of
bull’s eye for inserting beer can, the scoring remains the same except if axe hits
and draws liquid from can, that throw will be scored 6 points. Foul line is 20 feet
straight out from bull’s eye then down.
2. Final resting place of axe is scoring area. Points will be scored in the highest point
ring in which the axe is resting. If both points stick there will be no points given
for that throw. The axes must stick in the target until the judge removes or
instructs the contestant to do so.
3. Contestant must stand behind a foul line. Axe must be released before either foot
crosses the foul line. This rule will be enforced.
4. The axe must be double bitted of at least 2-1/2 pounds having an overall length of
no less than 24 inches and no greater than 40 inches as measured from the top of
the eye to the end of the handle. The blade width will not exceed 6 inches.
5. The leading edge of the axe shall be the scoring edge.
6. One practice throw and a minimum of 3 throws for score (practice throw may be
at the option of the show). If contestant does not wish a practice throw it is his
responsibility to inform the judge before starting his 1st throw.
7. Area behind target must be kept clear of people in an area of 20 by 20 feet. Axe
throw judge should be aware of the competitor’s feet crossing the foul line (even
as a follow-through) prior to the axe hitting the target.
8. After throw has been scored the score cannot be changed for any reason.
How to Make a Throwing Axe Target
1. Obtain a log round. Size requirements vary depending on regional competition
specifications. Check with your local chapter.
2. Determine the exact center of the round and place a nail in that location.
3. Tie a 2 inch long string around the nail with a pencil tied to the loose end.
4. Rotate the string around the nail so that the pencil makes a 4 inch diameter circle
(the bull’s eye).
5. Extend the string to 6 inches so that the next circle you mark will be 12 inches in
diameter.
6. Extend the string to 10 inches so that the next circle you mark will be 20 inches in
diameter.
7. Extend the string to 14 inches so that the next circle you mark will be 28 inches in
diameter.
8. Extend the string to 18 inches so that the next circle you mark (the outside of your
target) will be 36 inches in diameter.