A 1991 study , commissioned at the recommendation of the Governor 's Board of Inquiry in the wake of the 1989 Loma Prieta earthquake , found the seismic joints would " likely remain intact and functional after the next earthquake . " However , settling of the tube within its trench and the Loma Prieta quake had reduced the allowable movement of the seismic joints to as little as
1989 Loma Prieta earthquake
1989 Loma Prieta earthquake
Transbay Tube