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 about from the epicenter. From October 5, they reported that a substantial increase in noise was measured in the frequency range 0.01–10 Hz. The measurement instrument was a single-axis search-coil magnetometer that was being used for low frequency research. Precursor increases of noise apparently started a few days before the earthquake, with noise in the range 0.01–0.5 Hz rising to exceptionally high levels about three hours before the earthquake. Though this pattern gave scientists new ideas for research into potential precursors to earthquakes, and the Fraser-Smith et al. report remains one of the most frequently cited examples of a specific