However, if you've got a backup tape there's nothing from the current that will flip the bits on the tape itself.
There are good reasons to have the backup be off site (other physical calamities) - but the aurora isn't going to flip any bits on a backup. At worst, it will destroy the machinery from a surge from the grid and an extremely powerful one may destroy the machinery from arcing in the device itself (this would be extremely powerful)... but the media itself is fine.
The issue would be that wires start getting induced current in them ( https://en.wikipedia.org/wiki/Geomagnetically_induced_curren... ) that arcs and shorts out the device.
However, if you've got a backup tape there's nothing from the current that will flip the bits on the tape itself.
There are good reasons to have the backup be off site (other physical calamities) - but the aurora isn't going to flip any bits on a backup. At worst, it will destroy the machinery from a surge from the grid and an extremely powerful one may destroy the machinery from arcing in the device itself (this would be extremely powerful)... but the media itself is fine.