Experts in seismology are looking into the series of earthquakes that rattled the Salton Sea late September, prompting speculations that a major earthquake will soon hit Southern California. Scientists monitoring seismic activity in the area found that tremors occurring underground are deeper than what was previously expected, according to a recent study.
Scientists Baffled At A Fault Line's Seismic Activity
Small and deep seismic activities are quite difficult to measure, especially in urban areas due to the distance of earthquake monitors and the racket caused by traffic industrial areas. As such, researchers temporarily set-up quake detectors along the Newport-Inglewood fault (NIF), which snaked through an 80-kilometer stretch from Culvert City to Newport Beach.
By zoning out the noise, scientists were baffled at the depth and frequency occurring in the NIF when they compared the seismic activity to other faults in the area. They found that the tremors occured in the crust where they thought it to be too hot to start quakes, reported CBS News.
In that level of depth, the rocks aren't solid but are viscous instead. In NIF's case, however, the rumblings are occurring that far below.
"They are concentrated in what appears to be the deep continuation of the Newport-Inglewood fault down into the upper mantle," Jean-Paul Ampuero, a professor of seismology at Caltech, said. Studying these unusually deep shakings may shed light at which earthquakes can occur, as well as to better understand the fault's structure, according to the researchers.
Increasing Frequency Of Underground Tremors
Aside from the depth, the frequency also got scientists scratching their heads. Experts thought that earthquakes follow a scaling law that helps them predict the ratio between the number of small and large quakes that will transpire on a certain fault line.
"That ratio is generally constant. Along many faults we see the same ratio, though the actual numbers may vary," Asaf Inbal, the study's lead author and geophysics graduate student at the California Institute of Technology, said. "However, on the NIF we find that for the deeper sections of the fault, the number of the small earthquakes is much larger than the number of large earthquakes."
Changes in temperature, pressure or the mineralogy of the rocks at those depths were suggestions of the researchers on why the NIF is showing a different ratio. However, they did admit that further research is needed to identify what's really causing it.
Major Earthquake Event Expected To Occur In Oregon
But it isn't just Californians that need to brace themselves. Oregon is also at risk of experiencing an overdue massive earthquake event, according to KTVZ.
"The Cascadia subduction zone is the earthquake that's been getting a lot of media lately. It's a 9.0, just like they've had in Japan about five years ago. It would be major shaking along the western portion of the state," said Allison Pyrch, a geotechnical engineer.
Scientists at the Oregon State University agreed and said that there's a 37 percent chance of an 8.0 to 9.0 magnitude earthquake hitting within the next 50 years. Though the threat is extreme, the level of awareness isn't where it needs to be, Pyrch asserted.
