BLACKHAWK (CBS SF) – Following a 4.3-magnitude earthquake and a 3.5 aftershock in Contra Costa County on Tuesday, 50 technical partners of the U.S. Geological Survey’s ShakeAlert early earthquake warning system were successfully notified, according to a coordinator with the program.

While the system is not yet available to the public as a mobile application for the region, if it was, many residents across the Bay Area would have received a warning as soon as the shocks began at the origin near Blackhawk, 20 miles east of Oakland, according to Robert de Groot, coordinator for communication at ShakeAlert.

Earlier this month, Los Angeles County residents questioned the accuracy of ShakeAlert after the county’s mobile alert system failed to warn the public when two earthquakes with magnitudes 6.4 and 7.1 hit Southern California.

READ MORE: 4.3 Earthquake Near San Ramon Shakes Wide Area Of East Bay

The system was established in Los Angeles County with the goal of alerting the public in case of shocks with a magnitude greater than 5, and the Southern California earthquakes centered in Kern County were estimated to have shocks below 4.5 in Los Angeles County.

Officials with the USGS ShakeAlert Twitter account on Tuesday wrote that the city of Los Angeles is “in the process of reducing ShakeAlert delivery to Los Angeles County to MMI III (weak shaking).”

The USGS is reportedly also working on a notification system that would issue a Wireless Emergency Alert, described as an Amber Alert for earthquakes.

The system was tested with over 40,000 residents in West Oakland earlier this year, de Groot said.

Seismologists at University of California at Berkeley are also working to incorporate a ShakeAlert notification system into their MyShake mobile application for Bay Area residents.

“It is in its test phase,” said Jennifer Strauss with the Berkeley Seismological Lab.

Strauss said more updates about the status of the application will be available this fall.

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