Looking over a long period, the volume doesn't look too different from previous periods of time.

As to why we see spikes, could be any number of reasons. I do feel that's been a lot of positive developments for Hive recently, but its also true that for the most part cryptocoins often have a lot of volume with little news. I can think of two possible reasons: 1) wash trading and/or 2) a lot of technical traders (such traders often just start buying or selling because other people are doing so), possibly using bots that trade on momentum. So if someone tries to buy a lot of Hive, it can create an "avalanche" effect as other traders jump on the bandwagon (especially bots which are purely programmed to trade when they see a lot of activity).

I don't really get what you mean by a ninja mine 2 in this case. There's no way that new coins could be created when Hive forked from Steem without it being obvious on the blockchain (it's easy to see that overall supply didn't change).

I also suspect that most Hive whales keep most of their Hive staked onchain rather than on exchanges, as otherwise they lose staking and curation rewards (but this is just my guess). I try to avoid keep much on exchanges for this reason and also to avoid possible losses if an exchange gets robbed.

I know some people have moved Hive onto Binance to get interest from futures, but all that would be publicly visible (there would be large transfers to exchanges), and as far as I know that hasn't happened with regards to Hive whales.