California's Famous "Tunnel Tree" Fell...A Precursor to Massive Earthquakes? - P.O.W. Report

Wednesday, January 11, 2017

California's Famous "Tunnel Tree" Fell...A Precursor to Massive Earthquakes?

California's famous Redwood "Tunnel Tree" fell over the weekend during the worst storms and flooding California has seen in a long time: 


The tree, named for the tunnel that had been carved into its broad base 137 years ago, was located in the Calaveras Big Trees State Park and toppled Sunday.

The series of storms over the last few weeks in the Sierra Nevada have been very good to Lake Tahoe.

According to the National Weather Service, the lake has gained about 33.6 billion gallons of water since Jan. 1 -- and the lake has risen about one foot.

It's a big turn around from just a few years ago, when the drought had Lake Tahoe water levels reaching record lows. [Source]
In the East Bay, a woman was killed on a golf course in San Ramon when a tree fell on her.

And in Squaw Valley in the Sierra Nevada, wind gusts on Sunday hit 159 mph.

“It’s not over yet,” said Alex Hoon, a meteorologist in the National Weather Service’s Reno station.

The storm is expected to last until Thursday and will bring several feet of snow to lower altitudes, such as Lake Tahoe and Mammoth Mountain in Northern California, as well as cities in western Nevada and southern Oregon.

Coincidentally, I was also reading about scientists postulating a connection between floods and earthquakes:
Heavy rainfall can trigger earthquakes in what one scientist calls "disaster triggering disaster."

Shimon Wdowinski, of the University of Miami in Florida, first noticed a connection between storms and earthquakes last year.

The devastating magnitude 7.0 earthquake that hit Haiti in early 2010 came only 18 months after Haiti had been deluged by several hurricanes and tropical storms. (See "Haiti Earthquake Anniversary: Pictures Show Slow Recovery.")

And another large earthquake, a magnitude 6.4 temblor that rocked Taiwan in 2009, occurred only seven months after the area had been hit by Typhoon Morakot, which dropped 9.5 feet (2.9 meters) of rain in five days. Hurricanes are called typhoons in parts of Asia. [Source]
The latest study, presented last month in San Francisco at a meeting of the American Geophysical Union, suggests that water-management plans should take the potential earthquake risk into consideration.

Between 2006 and 2008, a team led by geophysicist Daniel Brothers of the US Geological Survey's Woods Hole Science Center in Massachusetts conducted the first detailed seismic survey of the Salton Sea, uncovering a previously unknown fault system running beneath the lake (D. S. Brothers et al. Nature Geosci. 2, 581–584; 2009). The team subsequently analysed data from 20-metre-deep cores pulled from the lake bed in 2003 during earlier work for the US Bureau of Reclamation. The cores showed layers of coarse sandy material laid down during floods — at the same time that seismic activity was known to have occurred.

"We found quakes happened about every 100 to 200 years and were correlated with floods," says Brothers. "The Colorado River spills, loads the crust and then there is a rupture." He says the team is "very confident" in its evidence for the existence of three flood-derived quakes, of roughly magnitude 6, which happened about 600 years ago, 1,100 years ago and 1,200–1,900 years ago. "Sediments don't lie," he says.

A quake of about magnitude 7 struck the southern San Andreas fault about 300 years ago; the next is a century overdue. One possible reason is the Hoover Dam: since its completion in 1936, the lower Colorado no longer floods. [Source]

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