A fault line that runs through California could be months ways from having would could be a 6-magnitude earthquake – setting off the first major seismic event in decades.
A new study determined that quakes happen around every 22 years at the Parkfield section of the fault line in central California, which runs through Eureka and ends just past Palm Springs.
The most recent was a 6-magintidue in 2004, which followed previous ones in a magnitude-6.7 in 1983, a 6.0 in 1966 and 1934 saw a 6.5-magnitude quake.
Parkfield is suspected to be nearing the end of its quiet period and an earthquake could strike the fault line this year, according to lead researcher Luca Malagnini.
Researchers determined that quakes happen every 22 years at the Parkfield section of the fault line in central California, with the last one hitting in 2004
The San Andreas Fault, seen here on Carrizo Plain in southern California, runs for hundreds of miles along the state and is the site of relatively frequent earthquakes.
Scientists have long been monitoring the San Andreas Fault Line that is predicted for the ‘Big One.’
If a major quick would strike, experts have predicted about 1,800 people would be killed, 50,000 injured and over 60 buildings would crumble – resulting in at least $200 billion in damages.
But while California is currently safe, a new study setout to see if there are warning signs to help residents prepare.
On September 28, 2004, an earthquake shook the area with an epicenter at the town of Parkfield that was home to just 37 people.
The quake felt across a 350-mile stretch of the state – from Orange County to Sacramento.
Scientists also clocked in 150 aftershocks following the seismic event.
Malagnini, director of researcher at the National Institute of Geophysics and Volcanology in Italy, told Live Science that he believes a quake is set for this year, but may not strike at the 2004 epicenter.
Even though the time window is approaching when there is likely to be another earthquake at the Parkfield section of the San Andreas Fault, the area is not making much seismic noise.
The team setout to uncover a possible pattern with the Parkfield quakes.
They analyzed measurements of the fault line leading up to six weeks before each seismic event, discovering there was a different kind of signal that seemed to indicate rock cracks opening and closing in the strained area.
Using almost 23 years of seismic measurements from the area, they determined that a ‘preparatory phase,’ which includes cracks opening and closing beneath the Earth’s surface, signals an upcoming quake.
When this happens, sound waves travel differently through the ground.
Their measurements are of something called ‘seismic wave attenuation,’ a scientific term that describes how soundwaves travel through rock. Waves naturally lose energy as they travel through rock, a process called attenuation.
Earthquakes are high-energy waves, but at a fault line there can be small waves that happen even when there is no quake.
Scientists have long been monitoring the San Andreas Fault Line that is predicted for the ‘Big One.’ Pictured is what Los Angeles could look like if a 6-magnitude earthquake hit
If a major quick would strike, experts have predicted about 1,800 people would be killed, 50,000 injured and over 60 buildings would crumble – resulting in at least $200 billion in damages. Pictured is what AI predicts Sacramento would look like after the Big One
And it’s these waves that the scientists measured. What they found was that certain types of waves lost energy more quickly in the six weeks before the 2004 quake, while others lost energy more slowly.
High-frequency waves attenuated – or lost energy – more slowly, while low-frequency waves attenuated more quickly as the quake approached.
The fact that there aren’t many volcanoes in the area helps the matter, the researchers wrote.
Because there are no nearby volcanoes, they can be more certain that the waves they’re measuring are actually from the building tension at the fault.
A new study determined that quakes happen around every 22 years at the Parkfield section of the fault line in central California, which runs through Eureka and ends just past Palm Springs
Earthquakes occur when the Earth’s plate sections move against each other. Usually this is the result of built-up tension from the plates pressing together.
So if the tension on a plate has recently been relieved elsewhere, it won’t cause a quake at the Parkfield section as soon.
With all of these dynamic processes happening at once, it is difficult to predict when and where the next quake will happen, and the researchers are not claiming that they can do it.
But they are optimistic that these types of measurements may someday lead to earthquake prediction systems.
The study was published in the journal Frontiers in Earth Science.
