There are two ways that a fork could occur. 1) 2 transactions happen at the same time and one of them happens to win. This is normal, and the loosing transaction simply re-transmits. This is also why you should wait (I think) ~5 minutes before you consider a transaction `validated`. 2) All of Asia (or another group) decides to fork. This is equivelent to all of Asia saying that they do not acknowledge all transactions made after a certain time. There are the same consequences as in a traditional currency when this happens.