During August, a similar event took place in which Bitcoin Cash split from the main BTC chain. When such a hard fork occurs, everyone holding coins on the original chain, receives an equal number of both Bitcoin, and whatever other asset is created in the process. It’s likely that the current surge in buying is driven by investors hoping to maximise their Bitcoin position before any fork takes place.
This will mean they’ll also receive the greatest possible number of Bitcoin Gold. The hope is that there will be enough support for the BTG chain and that exchanges will eventually offer markets in which to trade it and of course profit.