1989 Loma Prieta earthquake the State office of Emergency Services issued (for the first time in Bay Area history) short term advisories for a possible large earthquake, which meant there was "a slightly increased likelihood of an M6.5 event on the Santa Cruz Mountains segment of the San Andreas fault". The advisories following the two Lake Elsman events were issued in part because of the statements made by WGCEP and because they were two of the three largest shocks to occur along the 1906 earthquake's rupture zone since 1914. The 5.3 June 1988 and the 5.4 August 1989 events also occurred on previously unknown
Eastern span replacement of the San Francisco–Oakland Bay Bridge section was composed of a double balanced cantilever span, five through-truss spans, and a truss causeway. The original spans of the bridge east of Yerba Buena Island became the subject of concern after a section collapsed during the Loma Prieta earthquake on October 17, 1989. The replacement span is engineered to withstand the largest earthquake expected over a 1500-year period, and it is expected to last at least 150 years with proper maintenance. It had been known for over 30 years that a major earthquake on either of two nearby faults (the San Andreas and the Hayward) could destroy the