Earthquake rattles San Diego: 4.8-magnitude tremor shakes buildings with residents asking 'did you feel that?'

San Diego residents were awoken by a 4.8 magnitude earthquake that rattled the city and surrounding areas just before midnight. 

The quake prompted dozens of locals to flood social media to check if others had felt the shaking. 

According to the US Geological Survey, the earthquake struck in Imperial County, close to the California-Mexico border. The epicenter was around 100 miles east of San Diego.

A map provided by the USGS showed that the quake impacted a huge area of Southern California, through to Mexico's Baja California region. 

There were no immediate reports of any injuries or damage. 

One resident wrote on X: 'Felt it in mission valley. My bed shook. It woke me up.' Another joked: 'I live by San Ysidro and felt my couch move, I thought I was just dizzy!'

While another said: 'Woke my wife up in Carmel valley and she naturally is freaking out.'

Every year in California, millions participate in the ShakeOut drill, a statewide readiness program. 

The ShakeOut earthquake drills are coordinated by the Southern California Earthquake Center at the University of Southern California. 

The event focuses on the 'drop, cover, and hold on' mantra for basic personal safety but also includes such measures as passenger trains slowing down for several minutes. 

'We really do recommend that people make themselves a smaller target from those things that cause injuries,' said Mark Benthien, the SCEC communications director and lead ShakeOut organizer. 

The ShakeOut drill originated in California in 2008. The first one was based on a scenario of a magnitude 7.8 earthquake on the southern section of California's mighty San Andreas Fault. It's the type of disastrous quake that experts warn will happen someday — although they can't say when.

The drill has since expanded internationally. Schools, government organizations, companies and others sign up to take part. More than 10 million people were registered this year in California, and millions more worldwide, according to organizers.

Compared to 15 years ago, Benthien said, 'many, many more people are getting prepared, practicing earthquake safety each year because of ShakeOut.'