Seismologists: More Earthquakes Likely in Southern California—And They Could Be Even Stronger Than 6.4

Yesterday, Southern California experienced its strongest earthquake for two decades when a 6.4 magnitude tremor struck near the community of Ridgecrest—which lies about 150 miles north of Los Angeles—at about 10:34 a.m. local time.

While the quake has caused significant damage in Ridgecrest (population 28,000) itself—the community has declared a state of emergency—there have been no reports of any serious injuries either there or in the wider region. Fortunately, the epicenter was located far away from major population centers, limiting its impact.

However, seismologists say that the danger is not over yet and there are likely more earthquakes to come, some of which could even be more powerful.

"This does not make [the Big One] less likely," seismologist Lucy Jones told the Los Angeles Times. "There is about a 1 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."

In fact, there have already more than 150 aftershocks with a magnitude of 2.5 or greater, according to Robert Graves, a seismologist from the United States Geological Survey (USGS) quoted by CNN. The largest of these so far had a magnitude of 4.6.

The USGS predicts that over the next week or so, there could be as many as 700 magnitude 3 aftershocks, which, while minor, are large enough to be felt near the epicenter. Aftershocks tend to decrease in frequency over time but some have the potential to be relatively powerful.

"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."

The USGS also estimates that there is around a 9 percent chance of an aftershock with a magnitude of 6.4 or higher occurring in the next week.

The initial 6.4 quake was felt by millions of people in the region, including residents in the greater Los Angeles and Las Vegas areas, although no significant damage was reported in these major population centers.

The 6.4 quake is the biggest to strike Southern California since 1999. In October of that year, a 7.1 quake struck a part of the Mojave Desert. Luckily, the remoteness of the area meant that there was negligible damage.

Ridgecrest earthquake
A crack stretches across the road after a 6.4 magnitude earthquake struck the area near Ridgecrest, California, on July 4, 2019. Mario Tama/Getty Images