Cracks from an earthquake along Highway 178 from Ridgecrest to Trona in California on July 4, 2019. FREDERIC J. BROWN / AFP via Getty Images
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Earthquakes have historically been difficult to predict due to the lack of clear patterns and the fact that the moving and colliding of tectonic plates occurs over long periods. If they were able to be better predicted, many injuries and deaths could be avoided.
Now, an international team led by scientists from the Jackson School of Geosciences at The University of Texas at Austin (UT Austin) has successfully isolated a pattern of “foreshock” tremors in a lab, a press release from UT Austin said. Knowing what this group of smaller tremors that precedes an earthquake looks like offers hope for future forecasts.
“If we’re ever going to predict or forecast earthquakes then we need to be able to measure, characterize, and understand what’s happening right before the earthquake,” said study lead Chas Bolton, who conducted the research while a postdoctoral fellow at the UT’s Institute for Geophysics (UTIG), in the press release. Bolton is currently a research associate at UT Austin’s Bureau of Economic Geology. UTIG and the bureau are both part of the Jackson School of Geosciences.
The study, “Foreshock properties illuminate nucleation processes of slow and fast laboratory earthquakes,” was published in the journal Nature Communications.
Now that the research team has identified a pattern of foreshock tremors, they will replicate them in the real world. Bolton will begin that work in Texas, where the hope is to isolate patterns that are similar from measurements made by TexNet, the state’s seismological network, according to the press release.
“Earthquakes happen in irregular cycles, making it difficult to know when or where the next one may strike. Although seismic records show that tremors and other geological movements occur before large earthquakes, earthquake faults produce as many random rumbles as meaningful tremors,” the press release said.
For a long time, scientists have sought to find clues to help predict earthquakes. Bolton approached this problem by sifting through the seismic “noise” of lab-generated earthquakes to search for patterns.
Using a miniature fault made at a Penn State lab, the research team measured the earthquake cycles it produced. During their experiments, the two-inch-long fault produced a pattern of increasingly strong tremors that got closer together as the simulated earthquake approached. This pattern was different from those of slower or weaker earthquakes.
Bolton said the pattern was significant because it meant the tremors were connected to the main earthquake.
“It gives you a physical explanation for what’s controlling the foreshocks,” Bolton said.
It also provides a pattern for researchers to watch out for in the real world.
Detecting these patterns won’t be as straightforward with deep faults that span hundreds of miles. However, co-author Demian Saffer, director of UTIG, said the findings highlight the importance of connecting seismic monitors to real-world faults in order to detect subtle shifts in the Earth.
“If we really want to detect these precursory phenomena, we need sensors and long-term observatories that can monitor these creaks and groans to tell us how the fault is behaving in the lead-up to failure,” Saffer said in the press release.
Currently, Bolton is using an artificial fault that is three feet long at UTIG, which he said will aid in better understanding how the pattern could happen in nature. He is conducting these experiments in addition to his research at TexNet, where he will be looking at tremor sequences associated with earthquakes with a magnitude greater than five. He said he expects results within the next year.