California is at risk of a massive earthquake that will go down in history, geophysicists say, after the state recorded a record number of small quakes in 2024.
The warning comes just days after a 4.4 magnitude earthquake struck the Los Angeles area on Monday, near Los Angeles’ Chinatown.
“2024 has had more earthquakes than any year we’ve seen since 1988,” Caltech geophysicist Dr. Lucy Jones told reporters. “We should expect that to continue.”
Experts say a major earthquake in Southern California, typically defined as one measuring 7.0 or greater, could kill at least 1,800 people, injure 50,000, and cause more than $200 billion in damage.
“2024 has had more earthquakes than any year we’ve seen since 1988,” Caltech geophysicist Dr. Lucy Jones told reporters. “We should expect that to continue.” Above, a map of the 2024 quakes
Dr. Jones noted that it is a common misconception that an increase in mini-earthquakes reduces the stress in subsurface plate tectonics, making an area quieter and less susceptible to “The Big One.”
She warned locals that the opposite is true.
“The most consistent feature of earthquakes is the relative number of large and small earthquakes,” Dr. Jones told local authorities. KTLA 5 Morning News on tuesday.
‘For every magnitude seven you have 10 magnitude sixes, 100 magnitude fives, 1,000 magnitude fours, etc.’
“So if the frequency of (magnitude) four increases, then the chance of a larger explosion increases by about the same percentage,” the CalTech researcher explains.
In other words, the spate of small earthquakes in 2024 predicts, according to most seismologists, that a large, high-magnitude earthquake will occur soon.
The many small earthquakes of the past year have ended a relatively quiet era in Southern California. In the past two decades, there have been only five magnitude 4 earthquakes each year.
Monday’s small quake caused minimal damage, but local news did report that water was shooting from a crack along the side of Pasadena City Hall, where firefighters had gathered to help citizens
The mini-earthquakes of the past year ended a relatively quiet era in Southern California, where only five magnitude-four earthquakes have struck each year over the past 20 years.
In the decades before that, since 1932, this sunny region had seen an average of ten to twelve earthquakes with a magnitude of four or greater per year.
“So this is an active year, just like we’ve had in the past,” Jones said.
With just over four months to go, we will have already seen 13 earthquakes of magnitude 4 or higher in 2024.
Monday’s small quake caused minimal damage, but local news reported water was gushing from a crack in the side of Pasadena City Hall, where firefighters had gathered to help citizens.
And a study published in June in the journal Scientific progress appears to support Dr. Jones’ view on the risk of a major earthquake in the near term.
Using advanced underwater scanning techniques, scientists have mapped the Cascadia Subduction Zone, a 600-mile (965-kilometer) fault line stretching from southern Canada to northern California. The fault line has never been mapped in such detail before.
It turned out that the fault line splits into four segments, rather than one continuous strip like many other fault lines.
“The accuracy and this resolution are really unprecedented. And it’s an astonishing dataset,” Kelin Wang, a researcher at the Geological Survey of Canada who was not involved in the study, said NBC News.
The discovery could be even more disastrous, as it implies that the different tectonic plates can slide under each other, creating more pressure and therefore more powerful earthquakes.
The researchers concluded that the Cascadia Subduction Zone could produce an earthquake with a magnitude of more than nine on the Richter scale.
Above is a map of the 4.4 magnitude earthquake that struck the Los Angeles area on Monday, taken from a location near LA’s Chinatown
For comparison, the city of San Andreas in California could experience an earthquake with a magnitude of up to 8.3.
If an earthquake measuring over 9 on the Richter scale hits the U.S. West Coast, it could trigger tsunamis 100 feet (30 meters) or higher, kill more than 10,000 people and cause more than $80 billion in damage in Oregon and Washington alone, experts estimate.
“The return period for major events in this subduction zone is about 500 years,” Wang said.
“It’s hard to know exactly when it will happen, but compared to other subduction zones, it’s pretty late anyway.”