With a seismic magnitude of 3.3 on the Richter scale, an earthquake shook Los Angeles, California, early this past Sunday. In a report by the U.S. Geological Survey, the epicenter is believed to be a mile away from Chatsworth in the San Fernando Valley.

They said it happened at 3:00 a.m., with a depth of almost seven kilometers, or a little over four miles. So far, there are no casualties or injuries reported.

A data sample shows that California and neighboring state Nevada experience an average of over 230 earthquakes with magnitudes past 3.0 and below 4.0 annually.

Tremors in California

The most recent earthquake has followed after a swarm of tremors that had a magnitude of 3.0 and higher. The most recent one was last month, at 3.8 magnitudes. In the California area, the San Andreas Fault is responsible for most of the earthquakes that happen in the region, which has an average of two or three large earthquakes each year.

According to NASA's Jet Propulsion Laboratory in a study by the California Institute of Technology, last summer, a fault that runs from the San Andreas to Death Valley has begun to move for the first time in half a millennium.

Author of the research Zachary Ross expressed his team's surprise at the findings since they have not observed any changes in the Garlock fault for years.

"Here, all of a sudden, it changed its behavior," he said in an interview with the Los Angeles Times. He believed this was high time that the state improved the quantification of earthquakes.

Last summer, two consecutive earthquakes hit the region, from the 6.4 in the Mojave Desert to another 7.1, not including the aftershocks.

"We can't just assume that the largest faults dominate the seismic hazard," he added, referring to the potential of smaller faults that can create bigger quakes.

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An Earthquake Early Warning System

Currently, California is the first and only state in the nation to implement an Earthquake Early Warning System.

California Governor's Office of Emergency Services said in a statement last month that the system uses ground motion sensors planted across California to detect movement underground. "[The system] will notify Californians so that they can 'Drop, cover and hold on' in advance."

The system makes use of the Shake Alert earthquake early warning system, which sends alerts through two delivery systems: The first is MyShake, the app developed by the University of California, Berkeley Seismology Lab. The app, which is downloadable on the iOS and the Android, is only sent to people in the zones where the earthquake will occur.

The second is a wireless notification system. The Wireless Emergency Alerts system sends notifications via cellphone towers, according to the chief of the seismic hazards in the OES, Ryan Arba.

The wireless emergency messages would send notifications to devices about the incoming earthquake seconds before it happens.