The Northridge Earthquake in 1994 was a massive 6.7 magnitude quake that struck Southern California’s densely populated San Fernando Valley, destroying freeways and leaving much of the area without power for extended periods of time. The quake struck at 4:30 AM on January 17th, 1994 making yesterday the 25th anniversary of the disaster and incidentally on the anniversary, the San Francisco Bay Area experienced its second tremor in 2 days. As the LA Times reported, the latest tremblor struck at 6:11 a.m., with an epicenter less than a mile west of the western edge of the Caldecott Tunnel — about 2 miles southeast of the UC Berkeley campus and 4 miles northeast of downtown Oakland. An earlier quake, a magnitude 3.4, hit a day earlier at 4:42 a.m.
The East Bay is threatened by the Hayward fault, which has been called a “tectonic time bomb.” A landmark report by the USGS last year estimates that at least 800 people could be killed and 18,000 more injured in a hypothetical magnitude 7 earthquake on the Hayward fault centered below Oakland (the Northridge quake, on the other hand, occurred on a previously-undiscovered fault line). The Hayward fault runs through a very densely populated area and out of the region’s population of 7 million, 2 million people live on top of the fault which makes the prospect of a major quake particularly terrifying. The fault is one of California’s fastest moving, and on average produces a major earthquake about once every 150 to 160 years, give or take 70 or 80 years. The last major earthquake on the Hayward fault, a magnitude 6.8, had its 150th anniversary on Oct. 21.
Why This Matters: As the LA Times explained in another article, other than hospitals, state government has generally not set any mandatory rules for earthquake retrofits, and that has left it up to city and county governments to make decisions about seismic risks. In the Bay Area while the cities of Oakland, Berkeley and Fremont have required this retrofit, several others are still dragging their feet like Palo Alto which is home to much of the Silicon Valley tech industry and faces $2.4 billion in damages should a big quake strike. This is also the case in Southern California where cities are also ignoring warnings.