SACRAMENTO – As millions of people participate in the international Great ShakeOut exercise today, California is underscoring the importance of earthquake preparedness and the nation's first earthquake early warning system, giving millions of Californians extra seconds to take protective measures before a tremor occurs.

The Great ShakeOut is observed annually on October 17, the date of the 1989 Loma Prieta earthquake. This magnitude 6.9 earthquake left 63 people dead, thousands injured and displaced, and widespread damage to buildings and infrastructure.

California's nation-leading earthquake early warning system, launched under the leadership of Governor Gavin Newsom, notifies residents of earthquakes by deploying ground motion sensors throughout California. Since the program launched in 2019, 50 percent more sensors have been installed, making the system more accurate and able to deliver alerts faster.

Alerts from the MyShake app and earthquake early warning system were received on mobile phones up to 35 seconds before shaking from recent earthquakes began. Last month, that system alerted millions of Californians in Los Angeles, Orange and Ventura counties in advance of a magnitude 4.7 earthquake near Malibu. In August, it warned Californians across Central and Southern California of tremors from a magnitude 5.2 earthquake.