Huge Spike in Bitcoin Mining in Europe

[Etunem]

This has nothing to do with the hashing power.
As depicted it shows the most stable nodes. This has been discussed many times before. I think it represents the number of connections.
However, you won't find a mining farm in the Bunker 

[solex]

Berlin, eh?
Now that's someting I find interesting..

Ente

I believe the "supernode" in Germany on the OP's screenshot is nogleg

https://blockchain.info/hub-nodes

The globe is showing relaying nodes, not specifically miners.

[ecliptic]

Terahashs anonymously solomining their own full blocks mining via a Tor exit node in Germany, a shit ton of the exit nodes are there

(Solo block bitcoins on its own unique unused wallet are worth more than non-solo block coins because they are much easier to make anonymous and hide.  Tor + solo mined block is theoretically untraceable to anyone)

You'd have to be an idiot to associate significant hashing power with any IP that can be tracked to you without a massive amount of work, for many reasons.