This site: http://prop.hfradio.org/ had the Earth's magnetic flow updated several times a day. If I remember it was April 11, 2012 "they" stopped updating that info and eventually was pulled off the internet.

How could you prepare for this event? Find a cave?

You bring up a good question Wookie. It would depend how long the reversal took. The longer it took the worse it could get. Man has not been around long enough to witness one of these events. There is some good research that suggests as the field breaks down it does not drop to zero. In this process several temporary poles are formed before the field rights itself again with the opposite polarity. So some regions of the Earth would maintain some semblance of magnetic shield protection from the high energy particle radiation from the sun. Other places will not be as protected. Worse still is that these areas will be fluid in nature, constantly changing. If we had no magnetic field the solar wind would strip away our atmosphere. It is thought that this is how the planet Mars lost its atmosphere. Probably everyone on this forum has some idea what a coronal mass ejection (CME), plasma ejected from an active area of the Sun. Without the magnetic field this harmful radiation would bombard the surface and prove deadly for life. A weak, fluctuating field couples with a direct hit from a CME would not be good. We do know however that there have been many field reversals in the past and that plant and animal life continued. Mass extinction events in the fossil record do not seemed to be linked with pole reversal. Perhaps your cave suggestion is not a bad one, especially if you have an aversion to being irradiated as I do.

I do know of a few somewhat close to home. I have thought of this often. A cave (poor mans bunker) would shield you from several shtf scenarios.

I know, one of the nickle mines in Sudbury, should light up real nice. Much like a microwave oven. 😈