The 1989 Loma Prieta earthquake destroyed the similarly designed Cypress Street Viaduct in Oakland , California , with the loss of 42 lives . The 2001 Nisqually earthquake damaged the viaduct and its supporting Alaskan Way Seawall and required the Washington State Department of Transportation ( WSDOT ) to invest US$ 14.5 million in emergency repairs . Experts give a 1-in-20 chance that the viaduct could be shut down by an earthquake within the next decade . Since the Nisqually earthquake occurred , semi-annual inspections have discovered continuing settlement damage
2001 Nisqually earthquake
2001 Nisqually earthquake
Alaskan Way Viaduct