The expected effects of a major earthquake on the new eastern span of the Bay Bridge, which is under construction, have been explained by Caltrans in a new video simulation.

Construction of the new eastern span between Oakland and Yerba Buena Island, which will consist partly of a self-anchored suspension span and partly of a flat skyway, is expected to be finished by 2014.

The span is being rebuilt to better protect motorists from earthquakes. The western span was retrofitted to improve its performance in earthquakes.

Saturday marks the 20th anniversary of the 1989 Loma Prieta Earthquake, which knocked out a section of the eastern span, leading to the death of one woman.

The new video shows the new bridge rocking and wavering under the effects of an earthquake. It also explains a number of devices that are being incorporated into the bridge’s design to help protect it from earthquakes, such as cable bands, viscous dampers and shear link beams.