Shaken residents are cleaning up from two of the biggest earthquakes to rattle California in decades as scientists warn that both should serve as a wake-up call to be ready when the long-dreaded "Big One" strikes.

California is spending more than $16 million to install thousands of quake-detecting sensors statewide that officials say will give utilities and trains precious seconds to shut down before the shaking starts.

Gov. Gavin Newsom said it's time residents did their part by mapping out emergency escape routes and preparing earthquake kits with food, water, lights and other necessities.

A magnitude 6.4 earthquake Thursday and a magnitude 7.1 quake Friday were centered 11 miles (18 kilometers) from the small desert town of Ridgecrest, about 150 miles  (241 kilometers) from Los Angeles.

Some Californians, like Greg Messigian of Los Angeles, say they're already taking precautions. His wake-up call came with the 1994 Northridge earthquake that killed 61 people and caused $15 billion in damage. His San Fernando Valley home, located just above the fault line, was all but destroyed.

"We had brick walls around the perimeter that had all fallen down. We had cracks in the pool. Inside the house everything that we ever had on a shelf was broken. Television sets fell off the places where they were and cracked. Our chimney was broken. There were cracks in the walls."

With the help of earthquake insurance, Messigian rebuilt.

On Sunday, the retired schoolteacher was going over his preparedness kit, making sure he had everything he would need for the next quake.

Among the contents: Enough water to last a week, extra shoes and clothes, blankets, flashlights, batteries, food, a cellphone charger and food for the family dog. On top of that, he has an escape route planned and keeps one car parked in the garage and another in the driveway - in case the garage falls down on the car.

The 1994 quake was not the state's most devastating. The famous 1906 San Francisco earthquake killed 3,000 people. A 1971 San Fernando quake, centered not far from the Northridge quake, killed 65. The 1989 Loma Prieta quake that struck the Bay Area as the San Francisco Giants played Game 3 of the World Series killed 63. (AP)Â