* Astronomy

Blobrana · L

RE: Lake Tahoe tsunami

Blobrana · L

For more than a decade, scientists at Scripps Institution of Oceanography at UC San Diego have been unravelling the history of fault ruptures below the cobalt blue waters of Lake Tahoe one earthquake at a time. Two new studies by the Scripps research team offer a more comprehensive analysis of earthquake activity in the Lake Tahoe region, which suggest a magnitude-7 earthquake occurs every 2,000 to 3,000 years in the basin, and that the largest fault in the basin, West Tahoe, appears to have last ruptured between 4,100 and 4,500 years ago.
These studies, led by a team of Scripps researchers including Graham Kent, Neal Driscoll, Jeff Bab**** and Alistair Harding, collected new data on earthquake history along three active faults in the region. These new data suggest that the most recent ruptures along the West Tahoe and Incline Village faults each produced nearly 4-meter-high offsets. The most recent event along the Incline Village Fault occurred about 575 years ago.

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Blobrana · L

A massive underwater landslide in Lake Tahoe thousands of years ago caused a tsunami and left ripplelike stony ridges on the lake bottom, according to a new study.
Three scuba divers, a robot submarine and researchers from the University of Nevada in Reno and the U.S. Geological Survey spent two years surveying the bottom of Lake Tahoe to piece together the landslide's story. Their findings are being published in the November issue of Geology magazine.
The waves created by the slide travelled 12 miles and must have splashed tremendously high when they reached the lake's eastern shore, said survey leader James G. Moore of the Geological Survey.
The landslide weakened the Tahoe shore on the lake's west side where McKinney Bay is today, sending a cascade of boulders, rocks and soil plunging more than 1,500 feet to the lake bottom.
Researchers still haven't figured out what caused the McKinney Bay landslide. Moore speculated that a small-to-moderate earthquake could have triggered the slide.
Such an earthquake could happen again.
The scientists have not determined the date of the slide, but radioactive carbon dating and fossil evidence suggest it occurred between 7,000 and 15,000 years ago.
Other researchers have discovered at least two significant seismic faults on the lake floor. They estimate the faults could trigger earthquakes with a magnitude as high as 7 that could generate waves 10 to 30 feet high.

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