BERKELEY (KRON) – The ShakeAlert earthquake early warning system is still in a test phase in the Bay Area and along the West Coast.

But apparently, it worked on Tuesday when a magnitude 4.3 earthquake struck near Blackhawk.

Researchers at the UC Berkeley seismological lab say they were tipped off before they felt the shaking.

Jennifer Strauss’ had an alert pop up on her desktop Tuesday afternoon when it rumbled 7.5 miles east of Blackhawk.

“I got four seconds of warning before the shake, so this was a great example of how the ShakeAlert system can provide earthquake early warning for Bay Area residents even when the earthquake originates in the Bay Area,” Strauss said.

Strauss received the alert from her office at the UC Berkeley seismological lab.

She’s a regional coordinator for ShakeAlert Northern California.

“Four seconds gives you a couple of things. First, it gives you the knowledge that what you’re feeling or about to feel is indeed an earthquake and not just a big truck going by. Um, it would also give you enough time to drop, cover and hold on, which is generally the recommended advice for what you should do when you feel shaking,” Strauss said.

The ShakeAlert system is a pilot program sponsored by the U.S. Geological Survey.

UC Berkeley is one of several universities on the West Coast involved in the testing.

The system isn’t fully funded, and therefore can’t share warnings yet with the public, but Strauss says ultimately that’s the goal.

“The quake system that we have right now, ShakeAlert, um, is actively monitoring earthquakes usually above magnitude 3.5. That doesn’t mean that all communication methods are going to push out information for an earthquake of that magnitude,” Strauss said.

She adds the length of the warning is not fixed.

It changes depending on how far you are from the epicenter of the earthquake and the fault that shakes.