A series of small earthquakes have rocked the San Francisco area, sparking renewed fears that the San Andreas Fault is ready for a long-overdue serious seismic shift.
A 4.6-magnitude earthquake hit Monterey County in California on Monday morning, with nine smaller aftershocks being triggered. The tremors were felt 90 miles away, in San Francisco.
Annemarie Baltay, a seismologist with the US Geological Survey, told SFGate that the "swarm" of earthquakes and aftershocks were typical.
“It’s as if someone put an oil can into the fault and lubricated it,” she said.
But any action along the San Andreas Fault, running from the Gulf of California to the region of Cape Mendocino, has long been cause for concern.
Its last major earthquake was in October 1989, in Loma Prieta – a shift which killed 64 people and left 16,000 homes damaged. Southern California has over 300 faults, and the majority of the population live within five miles of one.
It is believed the San Andreas Fault could spark an earthquake of up to 9.2 on the Richter scale. Scientists predict that a 7.8-magnitude earthquake could kill over 1,800 people and destroy or badly damage 300,000 buildings and homes.
Unlike most natural disasters, earthquakes are notoriously hard to predict.
“Lots of seismologists have worked on that problem for many decades,” said Greg Beroza, a professor of geophysics at Stanford university.
He told Vox: “We’re not predicting earthquakes in the short term. That requires us to know all kinds of information we don’t have.”