Is major fault line in California about to blow? Most mini earthquakes since 1988 sparks fears of the 'Big One'

California could be at risk of a generation-defining massive earthquake, according to geophysicists, following 2024's record number of mini-quakes across the state.

The warning comes just days after a 4.4 magnitude earthquake rocked the greater Los Angeles area on Monday emanating from a site close to LA's Chinatown.

'2024 has had more earthquakes than any year we've seen since 1988,' Caltech geophysicist Dr Lucy Jones told reporters. 'We should expect this to continue.' 

Experts believe a major quake in Southern California- usually defined as 7.0 and up - could kill at least 1,800, leave 50,000 injured and cause more than $200 billion in damage. 

Dr Jones noted that it's a common misconception that spike in mini-earthquakes relieve tension in the plate tectonics underground, leaving a region more calm and less prone to 'The Big One.' 

She warned locals that the opposite is true. 

'The most constant feature of earthquakes is the relative number of large to small,' Dr Jones told local 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 your rate of [magnitude] fours goes up, your chance of having a bigger one would go up by about the same amount,' the CalTech researcher explained.

2024's wave of small earthquakes, in other words, portends a coming massive high-magnitude quake sometime soon, in the opinion of most seismology experts. 

The past year's worth of mini-quakes have brought to a close a relative era of calm in Southern California, which has seen only five or so magnitude four earthquakes each year for the past two decades.

In prior decades stretching all the way back to 1932, the sun-soaked region  averaged closer to 10 or 12 earthquakes of magnitude four and above each year.

'So, this is an active year, much like we used to see,' Jones said.

With over four months left to go, 2024 has already seen 13 quakes at four or above.

Monday's mini-quake led to minimal damage, but local news did spot water shooting out of a rupture along the side of Pasadena City Hall, where firefighters had assembled to aid civilians.

And a June study published in the journal Science Advances would appear to bolster Dr Jones' perspective on the risk of a major quake soon.  

Using advanced underwater scanning techniques, scientists have mapped the Cascadia Subduction Zone — a 600-mile fault line extending from southern Canada to northern California — in never before seen detail.

It has revealed that the fault splits into four segments instead of being one continuous strip like many other fault lines. 

'The accuracy and this resolution is truly unprecedented. And it's an amazing data set,' Kelin Wang, a research scientist at the Geological Survey of Canada who was not involved in the study, told NBC News.  

The discovery could prove more catastrophic because it implies that these multiple tectonic plates could slide under each other, creating more pressure and thus more severe earthquakes.

The researchers concluded the Cascadia Subduction Zone has the potential to unleash a nine-plus magnitude quake. 

California's San Andreas is poised for an up to 8.3-magnitude quake, for comparison. 

If an earthquake of over 9 magnitude struck the West Coast US it could generate tsunamis reaching 100 feet high or more, kill more than 10,000 people and cause over $80 billion in damages in just Oregon and Washington alone, experts estimate.

'The recurrent interval for this subduction zone for big events is on the order of 500 years,' Wang said.

'It's hard to know exactly when it will happen, but certainly, if you compare this to other subduction zones, it is quite late.'