It's because the earthquake's epicenter was in Kern County and the ShakeAlertLA system is designed to cover quakes that occur within L.A. County. latimes.com/local/lanow/la…
The app was only designed to alert users physically located in Los Angeles County if there is at least “light shaking.” Today's 6.4 magnitude quake was only registered as "weak shaking" in L.A. latimes.com/local/lanow/la…
For each whole-number increase in magnitude, the seismic energy released increases by about 32 times. That means a magnitude 7 earthquake produces 32 times more energy — or is 32 times stronger — than a magnitude 6. latimes.com/nation/la-fg-m…