More than 40 people received the warning through the MyShake app, which was created by @UCBerkeley and released publicly in October. Via @latimes https://t.co/S80OLSie6a

— UC (@UofCalifornia) December 18, 2019

In a milestone, California’s new statewide earthquake early warning cellphone app sent out its first public alert for a magnitude 4.3 earthquake that ruptured Tuesday in the mountains between the Central Coast and San Joaquin Valley. https://t.co/XRfS2HYlAb

— Los Angeles Times (@latimes) December 18, 2019

Yesterday in California, the @USGS_ShakeAlert earthquake early warning system sent the very first public alert to smartphones when a magnitude 4.3 earthquake struck on the San Andreas fault near Paso Robles.https://t.co/o2HtcVqMum

— PNSN (@PNSN1) December 19, 2019

By Jove it Works! Earthquake triggers California's early warning app for the first time, giving users 8.7 seconds of warning, https://t.co/mxPtPaBZbY

— Bill Schrier (@billschrier) December 18, 2019

Good news ... it works!https://t.co/6FPBo2ij3q

— FutureShift (@futureshift) December 18, 2019

캘리포니아 판 긴급 지진 속보 앱이 가동 후 처음으로 실제 지진 경보를 발신. https://t.co/HgS0QPk8N4

— 푸른곰 (@purengom) December 19, 2019

A milestone: Earthquake early warning system sends first public alert to smartphones in California https://t.co/99KO1AfHGT pic.twitter.com/h07ShS1H75

— Rich Tehrani (@rtehrani) December 19, 2019

Yesterday in California, the @USGS_ShakeAlert earthquake early warning system sent the very first public alert to smartphones when a magnitude 4.3 earthquake struck on the San Andreas fault near Paso Robles.https://t.co/o2HtcVqMum

— PNSN (@PNSN1) December 19, 2019

A milestone: Earthquake early warning system sends first public alert to smartphones in California https://t.co/47eweYxVDc

— Phyllis Ryherd (@RyherdPhyllis) December 19, 2019

A milestone: Earthquake early warning system sends first public alert to smartphones in California https://t.co/16b2mkr9nR

— Zach Ross (@zross_) December 18, 2019

The @MyShakeApp earthquake early warning system became available to the public in Oct. Two months later, it successfully sends out its first alert. #shakealert https://t.co/ErI8fDhKui

— Moore Foundation (@MooreFound) December 18, 2019

A milestone: Earthquake early warning system sends first public alert to smartphones in California. @MyShakeApp delivered that alert across central California. https://t.co/DCdnzVzWs4

— Richard Allen (@RAllenBerkeley) December 18, 2019

A milestone: Earthquake early warning system sends first public alert to smartphones in California https://t.co/oHJ3jhQWpa

— Greenspaceguy (@greenspaceguy) December 19, 2019

A milestone: Earthquake early warning system sends first public alert to smartphones in California https://t.co/XRfS2HYlAb

— Los Angeles Times (@latimes) December 18, 2019

the system took 8.7 seconds to issue an alert. #MyShake delivers early warning alerts in CA for magnitude 4.5 #earthquakes and greater#earthquake #shakealerthttps://t.co/wIDIrP7EUh

— James White (@itsjameswhite) December 18, 2019

A milestone: Earthquake early warning system sends first public alert to smartphones in California - via @UCBerkeley app #MyShake https://t.co/WAXuTdajoL

— Robert Sanders (@bobthesciguy) December 18, 2019

Earthquake triggers California's early warning app for the first time https://t.co/auOUifGDlx via @Mashable #disasterrecovery #emergencymanagement #earthquake #smem #California #DigitalTransformation #egov pic.twitter.com/6AY6T0D8k4

— ☎️ Crisis Comms (@CrisisSocMedia) December 19, 2019