Easy there sparky, I'm just the messenger. According to what I was told the building shook, swayed, moved when it should have been stationary. Secondly, I was also told that Mr. Amano uses some sort of cork board but it's not exactly cork it is made of a wood found in Japan that absorbed the shock preventing the tanks from cracking, similar to the mats but firmer and thicker.
Now do the mats relieve stress from the tank, of course it does. It also serves as a buffer if you will between the vibrating equipment like filters and such from transferring to the tank. It's like a sound dampening mat. It absorbs sound, vibrations from getting to the tank and relieves pressure points as well.
Have you ever worked with Dynomat or other sound dampening systems before? If you have same principle.