I assume you are on mainland. I am in Okinawa.
What an amazing project you have going there. I wish I could see it.
To what others have said about the quakes and typhoons...this place (okinawa anyway) is unbelievable when it comes to how it is built. We get quakes, typhoons, 100 degree weather for months on end, high humidity, and there isnt one crack in anything. I wouldnt be worried about the tank.