Umm... I could see that if the trigger points were inside the 33.3m radius... so he'd really only have to worry about it when he was deep underground even in any of those locations. 
"I was an Otaku before those kids came along and changed the meaning of the word."
-- HM "Howling Mad" Wilson to more than one team-mate.
Hear that thunder rolling till it seems to split the sky?
That's every ship in Grayson's Navy taking up the cry-
NO QUARTER!!!
-- "No Quarter", by Echo's Children
"I was an Otaku before those kids came along and changed the meaning of the word."-- HM "Howling Mad" Wilson to more than one team-mate.
Hear that thunder rolling till it seems to split the sky?
That's every ship in Grayson's Navy taking up the cry-
NO QUARTER!!!
-- "No Quarter", by Echo's Children