Both earthquakes hit in Berkeley on the UC Berkeley campus. Some people say the aftershock felt bigger and others say the opposite. They were very similar.
The aftershock happened while classes were taking place and many people were in the library when the earth shook for the second time on Thursday. The epicenter for the aftershock was just outside Cal's Memorial Stadium which is undergoing major renovations since the Hayward Fault runs right through the middle of it. So far, there is no word of any damage to the stadium or elsewhere in the Bay Area.
Regardless, people in Berkeley are feeling anxious.
"I just felt both of them and I'm not from here so that was my first time feeling an earthquake, but nothing dropped or anything. It was fine," said UC Berkeley student Vanessa Whatley.
"I grew up in the Bay Area, we've been practicing earthquake drills all our life, so I'm not too worried because I know what we have to do to be safe, but given that we're on the Hayward Fault in Berkeley, it's definitely an issue," said UC Berkeley student Shahryar Abbasi.
"I've lived here 32 years and I don't like this. I'm nervous," said Bay Area resident Nadine Marturano.
"It makes me very nervous now because I'm thinking if there have been two, are there going to be more? I don't want to be here for the big one," said New York tourist Janet Bernreuther.
As a matter of routine, BART interrupted service to give workers a chance to inspect the tracks and since then Thursday's service had a 15-minute system-wide delay.
A lot of people are wondering if Thursday evening's aftershock will be the end of it or will there be more to come.
USGS seismologist Walter Mooney told ABC7, "There certainly are aftershocks happening even right now which are very small. We call them micro-quakes and micro-earthquakes. So these are going to be happening all through the night. And there's a chance that they may feel say a magnitude 2.5 or magnitude 3 or magnitude 3.2. So I would not be surprised if people at 2 o'clock in the morning say 'Was that a quake?'"
Coincidentally, the quakes came on the same day as the California Shake Out ? a day in which millions of people take part in earthquake drills throughout the state.
Some Bay Area firefighters after both quakes and had to pull out their engines outside of the station which is standard procedure in case of aftershocks. Leaving the trucks outside helps firefighters respond quickly if there is damage or injury. There was no damage from either of the day's quakes.
You can check our earthquake preparedness guide here for more information on what to do during and after an earthquake, as well as how to prepare yourself, your family, and your home for a major quake.