When an earthquake struck California's Bay Area, the MyShake app alerted users. An expert explains its function and safety tips.

When most Americans think about earthquake country, one place comes to mind almost instantly. California. The San Andreas Fault. Big shakers in Los Angeles or San Francisco. That's the familiar mental image.

Many San Francisco Bay Area residents were jolted awake by a sizable earthquake early Thursday morning. The quake, with a magnitude of 4.6, according to the U.S.

Tremors beneath Northern California show hidden plate movement, helping scientists better understand where future big earthquakes may occur.

A preliminary 4.9 magnitude earthquake shook Santa Cruz County early Thursday morning, according to the United States Geological Survey. The quake, which hit at around 1:40 a.m., was centered in Santa Cruz County,

The most important fact about the San Andreas Fault is also the least satisfying one: scientists can measure rising risk, but they still cannot name the day a giant earthquake will begin. That gap between knowledge and certainty is why researchers focus on warning patterns instead of predictions.

A 3.3-magnitude earthquake struck about 12 miles northeast of Indio early Sunday, Feb. 1, in the same area where a stronger earthquake shook the Coachella Valley in mid-January. The quake was recorded at 1:20 a.m. Sunday, with a roughly 2.4-mile depth.