Since then, seven earthquakes have rumbled below the earthquake-stricken state which on top of the potentially catastrophic Hayward Fault line – a chasm between two massive plates of the Earth’s crust that extends hundreds of miles across the country.
There is also the San Andreas fault – a deadly line which runs through California and is one of the most seismically active regions in the world.
Residents fear an “inevitable” magnitude 7.0 earthquake or greater – known as the ‘Big One’.
According to the US Geological Survey, the most recent earthquake hit yesterday at 7.41pm (UTC time) – with a magnitude of 2.9.
On the same day, another 2.6 magnitude tremor hit along with a 3.1 quake at just gone midnight.
On Wednesday California was struck by two quakes of magnitudes 2.8 and 2.6, with another two on Tuesday January 9 measuring 2.7 and 2.9.
All the earthquakes struck along the Hayward Fault – a “tectonic time bomb” due to be struck by a huge earthquake at any moment.
In 2008, the USGS found there was a 99 percent chance of a huge quake hitting California, which sits on the San Andreas fault which is part of the “Ring of Fire”.
A report warned a huge quake of this size could kill 1,800 people, injure 53,000, and cause $214billion (£162billion) of damage.
Beneath California, the Pacific and North American tectonic plates are moving northward – although the former is moving quicker leading to a build up of tension.
A powerful earthquake in 1857 released some of this pressure, but much more still exists, and Robert Graves, a research geophysicist at USGS, suggests the Big One could be overdue by 10 years.
He told Raw Story: “The San Andreas fault in southern California last had a major quake in 1857 (magnitude 7.9).
“Studies that have dated previous major offsets along the fault trace show that there have been about 10 major quakes over the past 1,000-2,000 years… the average time between these quakes is about 100-150 years.”
San Francisco – where residents live with the constant threat of tremors – is no stranger to earthquakes.
A devastating 6.9 magnitude quake killed 63 people, injured 3,757 and damaged countless buildings in 1989.
And 3,000 were killed by a 7.8 magnitude quake in 1906 which levelled the city with its powerful tremors.