On Tuesday, ripples of a 5.2 magnitude earthquake south of Bakersfield were felt along the Central Coast... but not by everyone.
"I saw other people did, but I didn't," said one tourist who was visiting San Luis Obispo on Wednesday.
"My family felt it but I didn't," said another.
Kathleen DeFort and her husband are visiting San Luis Obispo County from Brussels, Belgium.
"I had read if we came here, we would experience earthquakes," DeFort said.
She says they didn't feel the earthquake, but they did receive a warning notification about it on their cell phones.
"At first, I was a bit scared. We were sitting in a restaurant at the time," she said.
Will Sani was at home in downtown San Luis Obispo when the quake hit.
"I felt like a little wave for about three seconds," Sani said.
"What many people felt last night, if you're ya know, 30, 40, 50 miles or even more from an earthquake this size, it's likely that you'll just feel sort of a gentle back and forth," explained Robert DeGroot, U.S. Geological Survey ShakeAlert Team Lead.
So why did some people feel the earthquake but others didn’t?
DeGroot says it has to do with the soil.
"We know that when seismic waves, for example, the energy from an earthquake enters very soft soils, that those waves slow down and they actually get bigger. So there are regions around the Central Coast, Arroyo Grande, potentially Avila, and other places nearby that are on softer soils," DeGroot said.
He adds that the current technology used to detect earthquakes allows notifications to be sent out to areas that may be impacted before people feel it.
"USGS and its partners have put sensors that detect ground motion, and there are over 1,100 of them just in California. Those sensors pick up ground motion and then move that information really quickly over to a processing center. This all happens over a matter of a few seconds," DeGroot said.
The epicenter of Tuesday night's earthquake was not near populated areas, which is why DeGroot says having these sensors all over the state is so important.
"Not only are they sufficiently technologically capable of doing what they're doing, but they're really robust. They can handle a lot of punishment, temperature changes, summertime, wintertime, rain, and all those other things," DeGroot said.
If you subscribe to the ShakeAlert notifications but didn't receive one on Tuesday, DeGroot says it may have to do with your sensitivity settings.
If your settings are on a lower magnitude, you'll receive more notifications.
"There are something like 50 earthquakes a day, so we have them all the time. So we have many, many, many more small earthquakes than large earthquakes," DeGroot said.
