(July 30, 2008)—An expert at CalTech says the earthquake that rattled Southern California Tuesday should be considered a drill.

The magnitude 5.4 quake wasn't the "Big One" scientists have long feared, but it was strong enough to rattle nerves and get people talking again about emergency plans.

A fire official in Chino Hills, where the quake was centered, says the region was "really fortunate."

It caused limited damage and only minor injuries.

Since Chino Hills was incorporated in 1991, much of the construction there is newer and built to modern safety standards.

Although it rocked Los Angeles and was felt as far away as San Diego and Las Vegas, Tuesday's quake was far less powerful than the deadly Northridge earthquake that toppled bridges and buildings in 1994.