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Secrets Below The Surface Of Lake Tahoe


Gordon Seitz, geologist, California Geological Survey

BY ERIK HELLING -- An unmanned submarine launched last week is examining three faults beneath Lake Tahoe. The faults produce earthquakes and tsunamis about every 4,000 years -- and the lake is almost due for another one. So, what does this submarine look like? And how does it work? We'll talk with one of the geologists who is studying the faults.

Gordon Seitz, a geological scientist with the California Geological Survey says the faults extend from the middle of the lake onto the shore. Although these faults are not as active as those in California, Seitz stresses their importance.

“Because the faults lie at the bottom of a very deep lake, there’s an associated hazard of when they shift, all of the water above the fault gets displaced.  That then generates a tsunami wave,” said Seitz.

To examine these faults, Northern Illinois University has commissioned a robotic submarine. The submarine was designed to be lowered through an ice hole to study arctic marine life. The Lake Tahoe launch is a test before it goes to Antarctica. Besides being stored close to Lake Tahoe in Alameda, its Arctic capabilities serve another ideal purpose.

“The sediments at the bottom of the lake were produced by glaciers during the last ice ages, so the sediments are very similar to Antarctica,” said Seitz.

It’s functionality in Lake Tahoe goes past that of working with glaciers, however. The unmanned submarine also features a seismic profiler, which Seitz believes will ultimately help with researching these faults.

“It’s basically like an ultrasound unit. It takes a sounding, and you can see the sediment layers down to a depth of about 200 feet, and it generates a sort of cross section,” said Seitz.

The submarine has gone through initial tests in Lake Tahoe in preparation for more in-depth dives next Spring.

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