A seismic retention assembly for retaining equipment supported on weigh modules in place during and after a seismic event. The assembly includes a seismic bracket with a mounting plate and a flange that extends beyond the weigh module, and with a retention aperture formed through the flange, located adjacent to the equipment. A retention fastener includes a nut fixed to the equipment in alignment with the aperture, and also a bolt that passes through the aperture and engages the nut. Clearance between the bolt and the aperture enables unimpeded operation of the weigh module during normal use, but limits movement during a seismic event.