I visited a couple of DCs in Tokyo, and the tours systematically feature a look at the anti-seismic system. It's actually pretty unimpressive : basically the seismic-protected part of the building is mounted on big rubber dampers, with some huge pistons thrown in for active attenuation. In taller buildings (I visited a DC with around 20 stories IIRC) the stories are not rigidly connected together, so that instead of swaying (and possibly toppling) during an earthquake, the building just kind of wobbles.

Very effective though, as the video shows. My visits were post-2011, and each DC had a record of the building's movement during the big earthquake; max amplitude on the seismic-protected part was a couple of centimeters, vs 50 cms or more for the rest of the building.