We're taking a closer look at the new technology used to send out an emergency alert during an earthquake.
This comes after many locals received an emergency alert on their phone moments after the earthquake near San Simeon on Monday.
USGS tells KSBY that Monday's earthquake was the first time that this new wireless emergency alert system was utilized in San Luis Obispo County.
In order for an alert to be sent to your cell phone, the earthquake must initially be estimated at 5.0-magnitude or higher.
On October 25, a 4.7-magnitude earthquake struck 11 miles northwest of San Simeon. In the minutes that followed, there was a 3.5-magnitude quake and a 1.9-magnitude aftershock.
"In all of California, we have about 50 earthquakes a day so these earthquakes, magnitude-4, magnitude-3 earthquakes are very frequent," said Robert DeGroot, USGS ShakeAlert Coordinator.
DeGroot says about seven alerts have been sent out statewide over the past couple of years.
"The seismometers of the ShakeAlert system picked up the shaking of the ground and moved that information to a processing center," DeGroot explained.
USGS says about 8 seconds later, a single alert was automatically delivered to people in an area where shaking met a level 4 intensity out of 10.
The number of people that received the alert is not something USGS can track.
You can also get an earthquake alert, if the quake is an estimated magnitude-4.5 or greater, by downloading the first state-sponsored app, MyShake.
It was created by the UC Berkeley Seismology Lab and the number of downloads are starting to add up.
"Right now, we're coming up on 1.6 million people across California," said Nate Ortiz, Assistant Director of Planning and Preparedness, Governor's Office of Emergency Services.
According to the California Office of Emergency Services, our state experiences about 10,000 earthquakes each year.
With the Great California Shake Out earthquake drill just last week, state and local agencies encourage residents to be prepared for the next one.
"Things such as after an earthquake what to do like turning off your gas or turning off your power, checking for water leaks, kind of like a checklist," said Scott Jalbert, County of San Luis Obispo Emergency Services Manager.
The wireless emergency alert system is the same system that delivers Amber Alerts so you do not need to subscribe to receive the message.
If someone near you received an emergency alert but you did not, FEMA says it could be due to lack of cell reception or when on a call, some mobile phones will not show an alert.