California Earthquake: 5.4 Magnitude Tremor Strikes State Day After 6.4 Quake

Just a day after a 6.4 magnitude earthquake rocked Southern California, the same area felt a strong aftershock measuring 5.4 on the Richter Scale.

The U.S. Geological Survey (USGS) recorded the strong tremor at 04:07 PDT (7:07 EST) in a location 16 kilometers west of Searles Valley, not far from the epicenter of the earthquake that struck on Independence Day. It had a depth of 7.1 kilometers.

There have been multiple tremors since the Fourth of July earthquake measuring under 5 in magnitude, mostly in the 2s and 3s. Experts had warned of further earthquakes, perhaps even stronger than the first.

The USGS calculated a 3 percent chance that within the next week there will be a quake stronger than 6.4. They advise California residents to be on alert to the threat of aftershocks, especially when near to vulnerable structures, and remember to drop, cover, and hold on.

At around 10:33 a.m. local time on July 4, the initial earthquake struck around 18 kilometers from the city of Ridgecrest with a depth of 10.7 kilometers. It was felt all across mid- and Southern California, as well as neighboring Nevada and Arizona.

Its strength sparked fears that the so-called "big one"—a catastrophic earthquake expected to soon occur along the heavily-populated San Andreas Fault—had finally arrived. Such an event is anticipated to cost many lives and cause substantial economic damage.

Those experiencing the earthquake uploaded footage of the moment to the internet. People can be seen sheltering beneath archways in their shaking homes and shop floors are strewn with broken glass.

Seismologist Lucy Jones told The L.A. Times that the latest earthquake was far enough away from the San Andreas Fault that any impact on it will be minimal.

However, Jones added: "This does not make [the big one] less likely. There is about a one in 20 chance that this location will be having an even bigger earthquake in the next few days, that we have not yet seen the biggest earthquake of the sequence."

The 6.4 earthquake was the state's largest for 20 years, since the 7.1 magnitude Hector Mine quake back in 1999.

The USGS predicts that over the coming days there could be as many as 700 magnitude 3 aftershocks. "On average, a magnitude 6.4 earthquake will produce an aftershock as large as magnitude 5.4, and about 10 aftershocks with magnitude 4.4 or larger," a statement from the USGS read. "Earthquakes of this size can cause damage, particularly close to the rupture."

California earthquake aftershock tremor
A car drives past a crack in the road on Highway 178, south of Trona, after a 6.4-magnitude earthquake hit in Ridgecrest, California, on July 4, 2019. FREDERIC J. BROWN/AFP/Getty Images