NEW ORLEANS, La. — The waves on large lakes carry a lot of energy. Some of that energy can penetrate the bottom and shore of the lake, creating seismic waves. These can shake the ground for kilometers (miles) around, a new study finds. Scientists now believe that recording those seismic waves could give them a load of useful data.
For instance, such data could help map underground features — such as faults —that point to possible earthquake risks. Or, scientists might use those waves to quickly tell whether lakes in remote, cloudy regions have frozen over.
Kevin Koper is a seismologist at the University of Utah in Salt Lake City. Several studies, he notes, have shown that lake waves can shake the ground nearby. But his team’s new study of six large lakes in North America and China has just turned up something interesting. Seismic waves triggered by those lake waves can shake the ground up to 30 kilometers (18.5 miles) away.
Seismic tremors are similar to the rolling waves on bodies of water. And in the new lake study, they passed by vibration-detecting instruments — seismometers (Sighs-MAH-meh-turz) — at a frequency of once every 0.5 to 2 seconds, Koper now reports.
“We didn’t expect that at all,” he says. The reason: At those particular frequencies, rock will typically absorb the waves pretty quickly. In fact, that was a big clue that the seismic waves had been generated by lake waves, he notes. He and his team couldn’t identify any other nearby sources of seismic energy at those frequencies.
Koper presented his team’s observations on December 13, here, at the fall meeting of the American Geophysical Union.
The researchers studied lakes having a range of sizes. Lake Ontario is one of North America’s five Great…
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