That spike may be the ~144'000 coins seized from Ross Ulbricht's laptop.
No, they are resting here:https://blockchain.info/address/1i7cZdoE9NcHSdAL5eGjmTJbBVqeQDwgw
http://www.walletexplorer.com/address/1i7cZdoE9NcHSdAL5eGjmTJbBVqeQDwgw
Then what could the spike be?