Securing heavy steel shelving unit (sitting on floor) to walls (earthquake prep)

I’m doing earthquake preparations. I want to secure two large, heavy, freestanding shelving units that sit on the garage floor to the adjacent walls.

The shelves are pretty thick steel (with particle board shelves), so they’re very heavy and large–guessing about 7-feet tall and about 7 feet long when assembled. About 20 inches deep. (The unit sits about 2-3 inches from the wall because of a protruding foundation that runs the entire periphery of the garage along the floor.)

We live in a condo apartment building with thicker drywall than I’m used to seeing and also steel 2x4s. I don’t trust the 2x’s alone to secure the units and I’m not sure about the drywall.

That said, my thought is to use a vertical 10" length of plumbers tape in two places, wrapping over the steel rim of the top shelf (between frame and wooden shelf), and secure each end of the tape to the drywall with a heavy-duty anchor, one above the shelf frame and one below, plus washers between screw heads and tape. (I’m NOT planning to anchor into the steel framing, just the drywall.)

**So two questions…

1. I’m I trusting the drywall too much here? Should I be anchoring to the metal framing?

2. If my plan is good enough, What size and kind of anchors would you recommend to attach the tape to the drywall…would molly bolts be enough or would you suggest using toggle bolts?

Apologies for the long question. I think you may need that level of detail.

Thank you!

Bill

 _^_______________^_______________^______________^_____  <-- screw locations
|______________________________________________________| <-- 2x6 board
     *   *                                 *   * <---------- chain
     *|-|*                                 *|-|* <---------- shelving upright
     *****                                 *****