Hello Digger-san. As a Japanese I really appreciate your offer
I too am going to Tohoku to do some volunteer work from this weekend.
If you are not fluent in Japanese, what you need is a volunteer group comprised of or including foreigners currently active in Tohoku region. There are some such organizations but the following is the only one I know of.
http://www.peaceboat.org/english/ind...ype=21&menu=62
I went to their orientation session and heard that the most wanted activity right now is sludge clearance. But I am not sure if you can utilize your skill as heavy machinery operator for them.
Are you in Japan now? I’ll let you know if I find any other organization that might suit you.