On Shaky Ground
There’s a lot of things that may come to one’s mind when they think of San Francisco, California. The Golden Gate Bridge, the growing tech industry in Silicon Valley, the birth of the hippie movement in the late 1960’s, the Castro district’s role as a historical safe haven for the queer community. But the one thing San Francisco is probably best known for is earthquakes.
The Great San Francisco Earthquake happened on the 18th of April in 1906. Rupturing the northern 480 km of the San Andreas Fault, the quake had a magnitude of 7.9 on the Richter scale and lasted for 42 seconds. It was felt from northern Oregon to Southern California. 80% of San Francisco was destroyed and more than half of the population was left homeless.
While the earthquake itself was massively destructive, the real damage came in the days following. Gas mains had burst all over the city, resulting in over 30 fires that destroyed more than 25,000 buildings. Jack London, who lived 40 minutes outside of the city in Sonoma County, was asked to come into the city and report on what he saw. Upon his arrival he wrote, “Not in history has a modern imperial city been so completely destroyed. San Francisco is gone! Nothing remains of it but memories...”
The “Next Big One” has been a cause for concern for Californians for decades, particularly after the Loma Prieta Earthquake of 1989, which had a magnitude of 7.1 but whose epicenter was about 130 km south of San Francisco, which brought the threat of these natural disasters back into the forefront of people’s minds. A 2006 study suggested that the San Andreas fault has reached a high enough stress level to potentially result in another 7 or higher magnitude earthquake.
Earthquake safety is an integral part to growing up in California. The California Earthquake Hazards Reduction Act from 1985 sought to implement research and development to increase public knowledge of earthquake safety and to ensure seismically safe building regulations moving forward. As a child, we had earthquake drills as often as fire drills in school, and I, still, at times find myself absentmindedly noticing a sturdy table or nearby doorway that could be used as shelter just in case. The new Salesforce Tower building, completed in 2017 and now the tallest building in the city at just over 320m, had to set revolutionary new benchmarks in seismic safety in order to be built.
However, one aspect of earthquake safety that may cause devastating consequences throughout the Bay Area in the event of the “Next Big One” is the potential liquefaction of reclaimed land. In many areas along the Bay, artificial fillers were used over estuarine mud to allow that land to be developed. Estuarine mud shakes much harder than bedrock during seismic events, causing more damage to the properties atop it, and there is a high likelihood that this land may also turn into a sandy liquid that provides no support to the structures it holds. There are warehouses, office buildings, historical and cultural landmarks, and people’s homes along this land from San Francisco to San Jose to Oakland. And as we saw in the 1906 earthquake, the earthquake itself isn’t always the main cause of destruction.
Land and housing shortages are already a huge problem in San Francisco, where property prices are soaring due to the influx of high salary employees in the tech industry and lack of new housing developments. So an immediate solution to this problem isn’t easy to find. However, the headquarters of many major tech companies, such as Facebook, Instagram, Twitter, and Google have been built in these high-risk areas, which may help push efforts to ensure these lands are earthquake safe moving forward.