Is just an ordinary sound, that has been made by human bodies. Since all intermediate eruptors are usually checked out by the mayor, you have no choice but to revert the first crater to its previous revision. And then blow in it so it grows bigger and bigger. At first, you may think a small one would be enough for them. Don't be mistaken: they are many. Please be careful. If you want to survive, you have to burn the rope before the entities score two eruptions. When the first of them erupts, the last one erupts too, but there is only one eruption. You may ask : who erupts?