Shake Alert app: The reason why some didn't receive the alert

LOS ANGELES (FOX11) - Did you receive a shake alert notification this morning about the 6.4 earthquake? If not then you're not alone.

According to the City of L.A. those in the Los Angeles area didn't receive a notification because the shaking was below 4.5. The app only sends alerts if shaking is over 5.0 in L.A County.

Following the quake several people took to Twitter to express their frustration and concern about not getting a notification. In a post online the City said "we hear you and will lower the alert threshold".

Seismologist Lucy Jones of Caltech says the shake alert computer system at Caltech's seismic facility registered a 48-second warning that shaking had begun.

Several aftershocks in the magnitude-3 range were reported by the USGS, as expected following a substantial quake. Jones said there was a better than 50-percent chance of a larger aftershock in the magnitude-5 area sometime this afternoon.