A series of earthquakes have struck close to a fault line in the US sparking fears of greater tremors around the so-called "Ring of Fire".
The earthquakes took place in Alaska and California, but the biggest one (with a 4.3 magnitude) hit the town of Perry in Oklahoma.
In total there were 13 quakes over the weekend but no reports of injury or serious damage. Warnings were still issued in parts of California after one of the quakes – measuring a 5.3 magnitude – struck near the Channel Islands in Southern California.
"A 5.3 could be damaging if it was right under our feet," John Vidale, director of the Southern California Earthquake Center told the LA Times .
‘It’s right on the edge of being an earthquake that could be dangerous. It’s a reminder that we need to be ready in the future.’
Ring of Fire
More worrying is the proximity of these quakes to the so-called "Ring of Fire".
This is the most active fault line in the world and stretches around the Pacific from New Zealand around the east coast of Asia, over to Canada and the USA (along the San Andreas fault) and down to the southern tip of South America.
More than 90% of the world’s earthquakes occur along this line as the continental plates grind up against each other.
The "Big One"
Experts are concerned the Ring of Fire is overdue a potentially devastating earthquake that could have huge repercussions across the southwest US.
"The San Andreas fault in southern California last had a major quake in 1857 (magnitude 7.9)," Robert Graves, a research geophysicist at the USGS, said last year.
"Studies that have dated previous major offsets along the fault trace show that there have been about 10 major quakes over the past 1,000-2,000 years," he said, according to the Express .
"The average time between these quakes is about 100-150 years.”
John Vidale told the LA Times there’s a 1-in-20 chance of these smaller earthquakes leading to a bigger one in the next few weeks.
Increased seismic activity
Seismologists have already predicted that the Earth is entering a period of increased seismic activity.
This prediction comes from the fact that the Earth is currently experiencing a periodic slowdown of its rotation.
Historically, these slowdowns have coincided with peak times for earthquakes and seismic activity.
"So far we have only had about six severe earthquakes [in 2017]. We could easily have 20-a-year starting in 2018,” said Dr Roger Bilham from the University of Colorado.
Bilham, together with Rebecca Bendick from the University of Montana studied earthquakes occurring since 1900 that measured over 7 on the Richter Scale. They found periods of five years where the Earth’s rotation slowed and these were followed by periods when seismic activity was heavier than usual.
“It is straightforward,” said Bilham. “The Earth is offering us a five-year heads-up on future earthquakes.”
These fluctuations are usually very small, sometimes slowing a day by no more than a millisecond. But according to their research it has an effect.
How and why is not yet known but it’s supposed that it could have something to do with behavioural changes in the the Earth’s core.
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