WordPress Hook after blog activation

I am new to wordpress,

Is there a hook that will trigger during a blog activation. I am working on a multisite, then I noticed that after the user registers, they have to activate their blog through clicking a link that was sent to their email.

I want to have a hook that after blog activation, I will get the blog’s meta then store it in the user’s meta.

Is that possible? I have been search the internet but can’t find an example or a hint.

Your help will be greatly appreciated!

Thanks!