It didn't seem to be an attack. The chain split off into 5 alternate chains at some point because of the very rapid increase of hash on the network. Its really not that much out the ordinary. Also Caliber has no Masternodes...
The only other time I've seen massive spikes like this (and it was a number of individuals exploiting the lack of hash via hashing services) was Electronium when they finally forked to CN7. Some individuals were hitting the network hard when the difficulty lowered, grabbed the coins then waited for it to lower again (leaving all the GPU miners to work through the difficult blocks). With the current increase/decrease wave it resembles the same.
Even this morning I watched the network go from 4M to 2M and looking at the graph it's been like that (major diff in hills and valleys for hash rates) the entire weekend.
I'm newer to joining recently released coins... have any informative material on the chain splitting because of the hash rate? (or anything really useful to explain it?)
Info is kinda all over the place when it comes to coins in general.