The time and date are forever linked, a lasting reminder of the day The City shook: 5:04 p.m. on Oct. 17, 1989.As Northern California marks the 30th anniversary of the Loma Prieta earthquake, a new series of temblors this week reminds us anew how the earth shook that October afternoon.The deadly 6.9-magnitude quake — the strongest earthquake to hit the Bay Area since the San Francisco quake of 1906 — devastated the region.