Waves in lakes make waves in the Earth

Waves in Lake Ontario [image credit: SYSS Mouse / Wikipedia]

Researchers say ‘a consistent signal emerges’ over longer periods. In theory the Moon should be a suspect given its role in tides?

Beneath the peaceful rolling waves of a lake is a rumble, imperceptible to all but seismometers, that ripples into the earth like the waves ripple along the shore, reports Phys.org.

In a study published today in the Journal of Geophysical Research Solid Earth, scientists at the University of Utah report that these small seismic signals can aid science.

As a record of wave motion in a lake, they can reveal when a lake freezes over and when it thaws. And as a small, constant source of seismic energy in the surrounding earth, lake microseisms can shine a light on the geology surrounding a lake.

“It’s kind of a new phenomenon,” says Keith Koper, director of the University of Utah Seismograph Stations and co-author of the study. “We don’t really know how it’s created.”

Discovering quaking lakes

Seismologists have long known that wind-driven ocean waves generate small seismic waves, called microseisms. These microseisms are generated as waves drag across the ocean floor or interact with each other. They are part of the background seismic noise in coastal areas.

“We’ve recently found that the waves on lakes actually generate these microseisms too,” Koper says. Lake microseisms had been previously recorded near the Great Lakes, Canada’s Great Slave Lake and Utah’s own Great Salt Lake. In the paper, Koper and colleagues present additional observations from Yellowstone Lake and three lakes in China, exploring the characteristics of the respective lakes’ microseisms.

Koper says the tremors are very small. “You wouldn’t be able to feel ’em, that’s for sure,” he says. But by averaging seismic signals over a long period—six months, for example—a consistent signal emerges.

Continued here.