Researchers have found a way to detect tiny earthquakes and they have now identified previously unknown tremors that occurred in Southern California over that last 10 years.
Undetected Quakes In Southern California
The catalog of quakes in Southern California for the period between 2008 and 2017 was just under 180,000, but many quakes were undetected.
To look for evidence of these small quakes, Daniel Trugman, from the Los Alamos National Lab, and colleagues used a technique known as template matching. The process relied on data from a network of about 400 seismic sensors in California that continuously measure the movement in the Earth's crust.
The researchers analyzed the data using a powerful array of computer processors, which revealed significantly higher number of tremors.
1 Earthquake Every 3 Minutes
Trugman and colleagues found evidence of 10 times as many earthquakes: 1.81 million temblors that occurred over the last decade.
The number is equivalent to having one tiny earthquake every three minutes. Most of these tremors were so small they had long been undetected because their signals were difficult to separate from noise.
"This effort resulted in a catalog with 1.81 million earthquakes, a factor of 10 increase, which provides important new insights into the geometry of fault zones at depth, foreshock behavior and nucleation processes, and earthquake triggering mechanisms," the researchers wrote in their study, which was published in the journal Science on Thursday.
The newly identified quakes may be too small to be considered dangerous, but the findings can help shed light on the geophysical process that may lead to more devastating "Big Ones." Experts fear that California is long overdue for a mega earthquake whose magnitude is expected to destroy properties and claim lives.
The ability to accurately predict the occurrence of these dangerous earthquakes is crucial.
"The holy grail of earthquake seismology has always been prediction," Trugman said. "I'm cautiously optimistic that we'll make progress on earthquake prediction."