Magnitude 5.1 earthquake shakes Southern California ahead of vicious storm arriving

As Southern California braced for a highly unusual summer storm on Sunday afternoon, residents were struck by a much more familiar phenomenon: a magnitude 5.1 earthquake, according to the US Geological Survey.

The epicentre of the quake was in Ojai, between Santa Barbara and Ventura, USGS data showed.

Shaking was felt throughout Los Angeles and surrounding communities, according to a USGS tool that allows residents to self-report their experience.

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At least two aftershocks — measuring 3.1 and 3.6 — followed the initial quake.

USGS seismic reports are preliminary and are sometimes adjusted.

Tropical Storm Hilary is unleashing vicious wind gusts and heavy rain across California, where officials have warned of catastrophic and potentially deadly floods.

Hilary's centre is just a few hours from Southern California, but the state has been feeling the storm's effects since early Sunday and the rainfall totals are starting to add up.

One California official has warned Hilary could be among the most devastating storms to hit the state in recent years.

In Arizona, authorities issued evacuation orders in parts of Lake Mead National Park urging residents to seek higher ground ahead of potential floods.

And Clark County, Nevada – home to Las Vegas – declared a state of emergency as the storm drew closer.

More to come.