"There is always the possibility that an earthquake can trigger a larger one," explained Zachary Ross, a seismologist at Caltech.
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It is important that we're prepared from the moment the earthquake strikes.
"These are the things that you really need to have in your earthquake kit," said Jeff Tateoisan, owner of Earth Shakes in Burlingame.
Prepare NorCal: Disaster Preparedness Resources
"We have water now that comes in 50-year shelf life. Wow! So you only have to replace it once," he added.
Tateoisan also sells food that keeps for 25 years.
"We have solar blankets, we have body warmers, you need to have light, we have light sticks, you need to have first aid," Tateoisan told us.
There are also some things you can do to protect yourself during an earthquake.
VIDEO: What to pack in your earthquake emergency kit
While some people still think it's safer to stand below a door frame, for decades we've known that it's better to actually drop, cover and hold on.