San Mateo–Hayward Bridge They provide power to the peninsula and San Francisco. The bridge was closed in the wake of the 1989 Loma Prieta earthquake as a precaution, but reopened on October 18, 1989. It underwent an extensive seismic retrofitting from 1997 through 2000 to protect against earthquake damage. The bridge was considered the worst evening commute in the Bay Area, which ended with the completion of a new eastern trestle carrying westbound bridge traffic in 2002. Eastbound bridge traffic took over the old trestle completely, although eastbound traffic was not expanded to three lanes until February 2003. Funded as part of BATA's
1989 Loma Prieta earthquake for the northern San Andreas Fault segment, the San Francisco Peninsula segment, and a portion of that segment which was referred to as the southern Santa Cruz Mountains segment. The thirty year probability for one or more M7 earthquakes in the study area was given as 50%, but because of a lack of information and low confidence, a 30% probability was assigned to the Southern Santa Cruz Mountains segment. Two moderate shocks, referred to as the Lake Elsman earthquakes by the USGS, occurred in the Santa Cruz Mountains region in June 1988 and again in August 1989. Following each event,