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Nearly Two Million Earthquakes Uncovered


Last updated 5/6/2019 at 9:25am

Even if you don’t feel it, it’s happening. Yes, an earthquake could possibly be occurring at this very moment. Every 174 seconds, the Earth’s tectonic plates are shuddering, trembling Southern California.

Scientists have counted about 1.8 million earthquakes in California from 2008 to 2017, amounting to at least 496 everyday, according to a new report published by journal Science April 18.

A new analysis revealed new information of seismic data about a plethora of previously undetected earthquakes, finding on average, a tiny quake happening about every three minutes; most were below magnitude one.

California is a seismic hotspot in the lower 48 states of earthquakes because of its many faults.

“It means the Earth is failing all the time,” lead author of the study Zachary Ross, said. Ross is a seismologist at the California Institute of Technology in Pasadena.

Ross and his colleagues scoured the Southern California Seismic Network’s archive, which holds data from 550 stations in the region that have constantly monitored the ground over the last 10 years, in search of previously overlooked earthquakes.

This data mining operation took 90 days’ worth of computing time. They were able to detect, understand, locate quakes more precisely, and created the most comprehensive earthquake catalog to date.

“This new information about triggering mechanisms and hidden foreshocks gives us a much better platform for explaining how big quakes get started,” co-author of the study Daniel Truman at the Los Alamos National Lab, said.

To find the smaller quakes, the researchers used an older method that is based on the premise that earthquakes from certain places have unique wave patterns. They looked for those quake fingerprints that wouldn’t normally be seen unless you look just for them. However, the process is quite tricky, as many of the signals are often hidden within the general noise that seismometers pick up. This includes shaking caused by construction, passing trains, and even the ocean waves.

With these findings, the team hopes to find a better understanding of the fundamentals about earthquakes, and hopes it will possibly help predict future earthquakes. The findings will also shed light in the gaps of the earthquake record, as well as learning how the triggering works.

Near an earthquake epicenter, aftershocks are brought about by the added stress resulting from the rearrangement of the Earth’s crust. But further away from the epicenter, aftershocks are triggered by the shaking itself. The study results thus suggest that the latter might play a more significant role than previously expected – a crucial finding that will help scientists better forecast the likelihood of aftershocks on various faults in the future. If those faults contain the potential to unleash catastrophic events, the aftershocks will only help prime the fault for a “Big One.”

The team also revealed a number of minuscule aftershocks, given that scientists do not yet understand the details of how earthquakes get going.

“If we could really predict when the next big earthquake will occur, we’re in business – that’s the Holy Grail in seismic hazard analysis,” Brugmann said. And added, they’re “not quite there yet, but this study is a step forward.”

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