ick! Earthquake

[Tuidjy]

Assuming the targets have 10 hit points and armour 10, the earthquake will fail to
injure 31.6%, kill 10.7%, and cause an average of 4.7 points of damage to everyone else.

If the armour is 15, the respective numbers are: 46%, 6.7%, and 3.71 damage to
the remaining ones.

(The above assumes everything hits. Defense has not been taken into account.)