A study conducted by the United States Geological Survey (USGS) observed three faults under California – which is particularly earthquake-prone – have been quiet for the last century. These faults are where some of the world’s tectonic plates – constantly moving sections of the Earth’s crust which make up continents – grind together, which should cause regular activity. Other parts of the world have been seeing major activity around these areas, and earthquakes with high magnitude are commonly detected. The three plates sitting under California have been muted, however, and experts believe this indicates an incoming period of seismological unrest.
California is situated above three particularly important faults, all of which carry a significant load.
The San Andreas, San Jacinto, and Hayward fault separate the Pacific and North American continental plates.
When these plates grind together, they can cause minor tremors felt on the surface, but the major concern is when these plates start to give.
The plates, at some point, are expected to push upwards, triggering a ground-rupturing earthquake.
There is no way for scientists to predict exactly when this might happen, but looking at the geological record gives an idea of exactly how the Earth should behave in this area.
According to data, the average number of ground-rupturing earthquakes per century is four, and researchers believe the next century will see more than this.
The last time a ground-rupturing earthquake was detected was in 1918.
Before then, there were six ground-rupturing earthquakes from 1800 to 1900, and a further two earthquakes between 1900 and 1918.
The figures suggest California is now overdue a number of earthquakes.
John Vidale, a seismologist and former director of the Southern California Earthquake Centre said the rate is expected to rise over the next century.
Talking to Mashable, he said: ”It’s reasonable that if there’s a long quiescence we would expect a higher rate for the next 100 years.”
Researchers for the paper authored by the USGS have said the probability of more earthquakes is now double what it would normally be.
Glenn Biasi, one of the paper’s authors, told Livescience.com: “The next century has to be busier than the last one.
“Our studies suggest that those probabilities are somewhat higher.”
Thankfully for Californians, this does not mean the state will see an earthquake “storm” nor does this mean an earthquake is imminent.
Mr Vidale said: “It’s not that [the odds of a quake] skyrocket.
“The danger might be doubled — but not everything is overdue. It’s not 10-months pregnant.”