LOS ANGELES (KGO) -- The 6.4 and 7.1 magnitude earthquakes that jolted Ridgecrest served as reminders of how unexpected and strong earthquakes can be.
Seismologists are still processing the data collected from both earthquakes.
Dr. Angela Chung with the Berkeley Seismology Lab explained how warning system alerts work, based on the data they receive.
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"If the San Andreas ruptures right here, we would have lots of time. 150 seconds of warning, but if it ruptures right here under San Francisco we probably wouldn't get much time, if any," said Chung.
Dr. Chung says they're getting faster at detecting earthquakes.
"I think it was about six or seven seconds between when the earthquake started and we detected it."
During Saturday's press conference Governor Gavin Newsom announced California's ShakeAlert system is still in the works.
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It's been in the works since 2006. The goal is to have 1600 sensors installed by the year 2021.
"The number 1,600 is based on the three states: California, Oregon and Washington. In California we are looking at 1,115 and of those today 70% of them have been installed," said Ryan Arba with California Office of Emergency Services.
Sensors are five to ten miles apart and sending data to places like USGS and Berkeley Seismology labs.
"The first wave which is the P wave you don't feel but our sensors will and through an algorithm it will generate an alert to where they'll expect a strong shaking to occur," said Arba.
On July 4 BART received an alert and took action.
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"The early warning and that automatically and that automatically slowed the trains no more than 27 miles per hour and trains that were in stations were automatically held," said BART's spokesperson, Jim Allison.
The ShakeAlert app is expected to be ready by the end of 2019.
The first test was rolled out in Oakland. The second test took place in San Diego County, and 3 million people received it according to COES.
In the next three months, a third test will be performed in the Bay Area in at least three counties.
See more stories and videos about the Ridgecrest Earthquake and general earthquake news and safety tips.
How close is California to a 'ShakeAlert' earthquake warning system roll out? Closer than you think