I can think of some ideas: parking the heads on hard drives is one.

Magnetic hard drives are sensitive to vibration. You can shout at hard drives and measure the effects (video: https://www.youtube.com/watch?v=tDacjrSCeq4).

One of the worst-case scenarios is a head crash. A head crash will damage the media and may result in data loss. https://en.wikipedia.org/wiki/Head_crash

My guess is that earthquakes powerful enough to cause a head crash are powerful enough for widespread destruction anyway, but I’m no expert. I did some quick searches for hard drives damaged by earthquake, and the only results I got were scenarios where the hard drives or the whole rack got knocked over by the earthquake and hit the floor.