Like many others we have adopted a lateral free-range filing system over the floor in the living room and garage. While that is my preferred natural state, at some time much of it will need to go back to the shelves. Chances are there will be a big wobble shortly after and it will end up on the floor again.
Gail has found a company SRNZ (Seismic Restraints NZ) that sells bits and pieces for keeping stuff in place during a shake. Some of the items look pretty useful, and in later times when excesses have gone sky-high may save a lot of hassle and money.
Their website is here and they have a catalogue and price list on-line.