Highest number of earthquakes reported in the state since 1988, sparking fears that a major quake could occur in the near future
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After a spate of earthquakes in California over the past week, researchers are now concerned that the uptick in earthquakes could forewarn further, higher magnitude quakes in and around the area. Already this year, there have been 13 reports of 4.0-magnitude or greater earthquakes in the state.
‘2024 has had more earthquakes than any year we’ve seen since 1988,’ said seismologist and researcher at the California Institute of Technology, Dr. Lucy Jones.
On Monday – after a 5.2-magnitude quake near Bakersfield – the Highland Park area of Los Angeles was hit with a 4.4-magnitude earthquake along the Puente Hills thrust fault system – a stretch of fault lines that extends from southern San Gabriel Valley to downtown Los Angeles and Hollywood. While no deaths were reported, a water line in the Pasadena City Hall ruptured and caused employees to evacuate. And only yesterday, a 3.9-magnitude earthquake was reported outside the city of Lake Elsinore, around a hour from Los Angeles.
Potential further earthquakes on the Puente Hills fault could cause 3,000-18,000 deaths, up to 735,000 displaced households and more than $250 billion in damage, according to research by Southern California Earthquake Center (SCEC) and US Geological Survey (USGS).
How common are earthquakes in California?
With more than 500 active faults, and 15,600 known faults – of which scientists are discovering more – California is no stranger to earthquakes. There is a 75 per cent chance of one or more magntiude 6.7 or greater earthquakes striking California in the next twenty years. And although recent, smaller magnitude earthquakes have occurred, Jones cautions people about assuming this means a greater magnitude earthquake will be avoided.
‘The most constant feature of earthquakes is the relative number of large to small,’ she said. ‘For every magnitude seven, you have ten 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.’
Scientists believe that the Puente Hills thrust fault system in California responsible for Monday’s earthquake in Highland Park is far more dangerous than the San Andreas Fault that caused the 1987 Whittier Narrows earthquake – a 5.9-magnitude quake occurring 12 miles east of Los Angeles resulting in 200 injuries, eight deaths and damages estimated at $358 million. Around 9000 people were displaced in and around the local area, while 10,000 structures were either damaged or destroyed. The San Andreas Fault is a 1300km (800 mile) fracture extending from the northern end of the Gulf of California to the Pacific Ocean near San Francisco.
A study conducted by the US Geological Survey has indicated that a region of the San Andreas fault – near Tejon Pass – may be overdue for a major earthquake, which typically occur once every 100 years. The last major earthquake occurred here back in 1857 – the magnitude 7.9 Fort Tejon quake – one of the largest-recorded earthquakes in the United States, and the largest in California, killing two people. If such a quake occurred today, damage would be in the billions of dollars. Since 1857, communities including Wrightwood, Palmdale, Frazier Park, and Taft – with a total population of over 177,000 people – have been created near the rupture area.
‘We’re thinking about the Puente Hills (fault system) because we had the earthquake right now, but everybody in Southern California lives within five miles of an active fault,’ said Jones. ‘We are riddled with them, and you can’t live here worrying about any one particular fault. We don’t know which one is going next.’
