I mean Christ, that's ridiculous. And the hash power has been increasing over the last week. Is this a botnet or something? How else would it be possible to have that much power, AND a steady increase?
It's a chinese "mining plant". They're using super-powerful chips which can mine BTC and LTC at same time. One chip can perfrom 84 KH/s peak performance and price is 65 USD.
If all 700 MH/s is coming from these computer chips it means this group of people has over 10 000+ and slowly increasing.
so, making some calculations, these people paid probably around 650,000.00 USD for 10,000 units "Gridseed GC3355" (plus PCB engineering and assembling costs ) for having 600 Mh/s for LTC mining, and 22.5 Th/s for mining BTC ...
the famous chip --> Gridseed GC3355 -Hybrid Scrypt/SHA256 ASIC https://bitcointalksearch.org/topic/gridseed-gc3355-hybrid-scryptsha256-asic-355268
data sheets --> https://github.com/gridseed
65 USD ist the price for evaluation samples. They probably got them a lot cheaper in bulk.