The seismologist ABC7 News spoke to didn't even feel the earthquake at his home because his home is built on some solid shield. He's been researching the quake since it hit at around 9:00 p.m.
He's been comparing it to some quakes that had happened in the early 1990s, and he said the difference with this one is that it was a lot deeper, which means it didn't shake things above it as hard.
"The earthquake this evening was 10 miles deep, so given that it is the same size, it would be twice as far away from those structures so they won't feel as strong. However as you go deep, the seismic waves tend to spread out further, so there is a lot more homes and a lot more structures let's say from a 10-20 mile distance than we would be able to say five miles deep. So you tend to get something more widely felt as it goes deeper," said UC Berkeley seismologist Robert Uhrhammer.
When asked about the chance of another one, Uhrhammer said there is anywhere between two to a 30 percent chance of another 4.0 quake happening in that area in the future.