My google hits jumped in the last 24 hours; is there a way to find out why/how/what keyword was used

Hubpages doesn't seem to give this info. It's one feature I always liked about Squidoo, but Hubpages is better overall.

Anyway, to answer your question: you should use Google Analytics. Instructions are here:

http://hubpages.com/guide/stats/analytics

I just went through this process last night, and now have neat reports to view on the traffic patterns on my hubs. Way more info than I need at this point :-)

As mentioned by Jeffrey, Google analytics is the best way to get info on what keywords/articles got you the most visits including when etc... However, you have to add the pages you want to view this.