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Oct. 2, 2000
Geologists have discovered evidence that a fault under the Great Salt Lake carries a strong risk for a future earthquake.
Science Specialist Ed Yeates reports the evidence was uncovered aboard a special research barge that was on the lake this summer.
Geologists know a lot about our east flanking Wasatch Fault because they've dissected it with huge trenches.
But what about a notorious fault which is out of sight deep beneath the Great Salt Lake?
It's one of several segments extending off this Oquirrh Mountain Fault just south of the Lake.
Underwater, the segments break into Antelope, Fremont, Promontory and the East Great Salt Lake Fault.
For the first time, the United States Geological Survey's Global Lake Drilling barge has continuously probed below the lake - pulling up sediments which could reveal how often earthquakes occur on this fault. The East Great Salt Lake Fault probably pitches to an angle much like the Wasatch Fault - and like its eastern cousin - produces very large earthquakes.
DAVID DINTER, U OF U GEOLOGIST: "THE EAST GREAT SALT SALT FAULT WILL PRODUCE A MAGNITUDE 6.8 TO MAGNITUDE 7.0 EARTHQUAKE. IT HAS DONE SO REPEATEDLY IN THE PAST AND THERE'S NO REASON TO THINK IT WILL STOP."
ED YEATES, SCIENCE SPECIALIST: "IN AN EARTHQUAKE, THE FAULT UNDER THE LAKE COULD DROP OR SLIP AS MUCH AS EIGHT TO TEN FEET. ON THE SURFACE THAT COULD PRODUCE SORT OF A LAKE VERSION OF A TSUNAMI."
As the fault slipped and displaced water, eight to ten foot waves would inundate shorelines in Clearfield, Syracuse and Layton.
But David Dinter says the energy released under the lake would do far more than just slosh around water.
David Dinter: "THE MAJOR CONCERN IS GROUND SHAKING FROM OGDEN ALL THE WAY DOWN TO SALT LAKE CITY, SANDY AND ALSO THERE'S VERY HIGH LIQUEFACTION POTENTIAL AS FAR EAST AS ABOUT 500 EAST."
Ground shaking would also hit hard in the Tooele and Skull Valley areas west of the city.
David Dinter says it will take several months to analyze samples from the lake. If quakes on the fault hit every 1,500 years or so - the data should show when the last big earthquake occurred.
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