The Earthquake Spell is a spell added in the July 1, 2015 update.
It deals a percentage of damage to all buildings within its area of effect, except for Gold Storage, Elixir Storage, and the Dark Elixir Storage.
The second Earthquake Spell dropped on a structure will do 1/3 the damage of the first spell, the third will do 1/5th, the fourth will do 1/7th, and so on.
A level 10 Town Hall cannot be destroyed with this spell, but its health can be pulled down to 1,275 hit points using 1 Earthquake Spell and 5 Lightning Spells. You can, however destroy a level 7 Town Hall with 1 level 3 Earthquake Spell and 4 level 6 Lightning Spells.
4 Earthquake Spells, regardless of their level, can take down any level of Walls.
Successive Earthquake Spells on the same building do significantly less damage, but successive Earthquake Spells against the same Walls do more damage
